ORIGINAL RESEARCH
Parachuting and Pregnancy: What Do We Know About Pregnant Skydivers and the Risks They Are Taking? Florian Ebner, MD,* Achim Wöckel, PhD,* Wolfgang Janni, PhD,* and Helen Paterson, MMedSc†
Objective: There is little medical knowledge about the risks of
antenatal programming, or short-term hypoxia and pregnancy outcome in pregnant skydiving women and their offspring.
skydiving during pregnancy. Some national parachuting associations ask for a doctor’s permission; others recommend not jumping at all during pregnancy. This article provides survey data and a literature review of pregnancy and parachuting/skydiving related issues to help the pregnant skydiver and her obstetrician make an informed decision. Survey data presented include pregnancy, delivery, and parachuting information from skydivers who jumped during pregnancy.
Conclusions: Pregnancy itself is a risk factor for injuries. Injuries in pregnancy are clearly associated with an unfavorable pregnancy outcome. The recommendation “do not skydive during pregnancy” is the safest approach. A possible lesser risk alternative to skydiving could be wind-tunnel training.
Design: International retrospective anonymous online questionnaire considering the Checklist for Reporting Results of Internet E-Surveys (CHERRIE). The PubMed database was searched with using the terms “skydive,” “pregnancy,” and “parachute” (query April 2013).
Setting: Web page questionnaire on skydivers’ epidemiology, experience, and pregnancy-related information. Participants: Fifty-seven parous female skydivers. Assessment of Risk Factors: Information on athletes’ experience, weather conditions, obstetric history (gravida, gestational week), delivery mode was obtained. Main Outcome Measures: Epidemiology of pregnant skydivers and literature review to provide information on skydiving risks. Results: Women do actively decide to skydive while pregnant. The majority of our participants were between 25-year-old and 35-yearold primips with 100 to 1000 jumps experience, answering the questionnaire from a European IP address. Precautions are taken in terms of weather conditions, gear, or sports partner. The literature review found no relevant literature regarding the question. Literature is searched for risk factors that come close to the ones in skydiving (ie, oxygen saturation, shock forces, and others). Further studies are needed to show the long-term effect of stress or low O2 saturation on
Submitted for publication June 3, 2013; accepted December 6, 2013. From the *Abteilung für Frauenheilkunde, Universitätsklinik Ulm, Ulm, Germany; and †Department of Women’s Health, Dunedin Hospital, Otago University, Otago, New Zealand. The authors report no conflicts of interest. F. Ebner initiated the study, made the connection to the parachuting associations, and wrote the article. H. Paterson contributed to the questionnaire and reviewed the article. W. Janni and A. Wöckel reviewed the article. All researchers had full access to all of the data. Corresponding Author: Florian Ebner, MD, Abteilung für Frauenheilkunde, Universitätsklinik Ulm, Prittwitzstr, 43, Ulm 89075, Germany (dr.ebner@ web.de). Copyright © 2014 by Lippincott Williams & Wilkins
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Clinical Relevance: This article provides insights into the pregnant skydiver’s decision making regarding the sports. In combination with the literature review, we provide up-to-date easy to understand information on the possible risk factors. This is a valuable source of information for the care providers of female skydivers to understand and compare the risk factors of this sport. With this information, the professional recommendation and relationship are strengthened. This article also guides the need for further research. Possible research areas include pregnancy and sports-related risk factors, placentation and prenatal programming, physical and psychological factors associated with skydiving. Key Words: pregnancy, skydive, parachute, skydiving, pregnant, sport, hypoxia, risk, delivery, altitude (Clin J Sport Med 2014;24:468–473)
INTRODUCTION Extreme sports are becoming more common. It can be challenging for doctors and health care professionals to be consulted for advice by an extreme sports practitioner, such as a recreational parachutist (skydiver). According to the United States Parachuting Association (USPA), the average skydiver is male, aged 31 to 39 years and has 26 to 500 jumps. They report 97.5% of participants are injury free, and only 28% have attended the USPA security day.1 Depending on the situation (weather, financial), skydivers can make 10+ jumps a day. The 2010 safety report of the International Parachuting commission (IPC) technical and safety commission states a fatality rate of 1 in 97 000 jumps. The 2 leading categories for fatalities were landing errors or fast canopies/intentional fast landing.2 There is little medical knowledge about the risks of skydiving during pregnancy. General risk factors for skydivers include low oxygen saturation at high altitudes and mechanical forces during canopy opening or landing. This article aims to give basic information about leisure parachuting (skydiving) and assess possible risks for pregnant Clin J Sport Med Volume 24, Number 6, November 2014
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athletes; therefore, the skydiving behavior and adaptations made by pregnant skydivers are investigated. This information will help pregnant skydivers and their obstetricians to make an informed decision.
METHODS An anonymous online survey was developed consistent with the Checklist for Reporting Results of Internet E-Surveys (CHERRIE) guidelines (Table 1) for female skydivers with experience of skydiving during pregnancy.3 The link was sent out to the International Parachuting Commission (FAI/IPC) and national parachuting federations directly. This included 9 of the top 11 federations in terms of membership and jump numbers (IPC). 2 Additionally, it was posted in online discussion forums on skydiving and pregnancy. One of the authors (F.E.) has been judging skydiving events internationally for 10 years; therefore, the survey was also sent to skydivers known to him to disseminate. The survey asked for basic obstetric information to get an overview of the obstetric situation. We included a question on pregnancy complications but deliberately did not ask for details of adverse pregnancy outcomes or information on the child’s development, as this might have led to a participation bias. Also, we were interested in the experience of the skydiver and the security measures taken. During pregnancy, most women seek professional and semiprofessional advice. Therefore, we asked who supported them in their decision to continue skydiving. Ethics were granted by the University of Heidelberg Ethics Commission under the trial registration no. S-436/2011.
Systematic Literature Review The National Library of Medicine (PubMed) was queried for the search terms “skydive,” “pregnancy,” and “parachute” without restrictions regarding date, journal, or language. The literature results were reviewed regarding relevance.
TABLE 1. Survey Questions How old were you at the beginning of the pregnancy?* Was this your first/second/third pregnancy? How many skydives did you have before the pregnancy and how many skydives did you do during the pregnancy (including those when you could possibly be not aware of the pregnancy)?* Roughly when did you stop skydiving during your pregnancy? (Normal pregnancy is 40 wk)* What other circumstances did you consider to increase the safety? Were there any complications during the pregnancy? When and how did you deliver?* When did/do you go skydiving again? Who supported you in your decision to continue to skydive? Do you have any other comments that you feel could add value? *Obligatory questions.
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RESULTS Survey The questionnaire page was visited 62 times; 57 questionnaires were completed between September and November 2010. The questionnaire was answered from IP addresses around the world. The majority of participants logged in from Europe with Germany (n = 16), Finland (n = 12), England (n = 4), Italy and Netherlands (each n = 2), and Austria, Slovenia, and Switzerland (each n = 1). The USA and Australia (each n = 6) and New Zealand (n = 3), Brazil, Russia, and South Africa (each n = 1) added to the poll. Twenty-three participants were aged between 25 and 30 years, 16 aged between 31 and 35, and 15 participants aged over 35. Only 3 participants were under 25. Forty-six participants were primiparous. Only 3 of the participants had less than 100 jumps before pregnancy, 25 had 100 to 500 jumps, 11 had 500 to 1000 jumps, 5 had 1000 to 2000 jumps, and 12 had more than 2000 jumps. Twenty-one participants stopped parachuting in the first trimester, and a further 13 stopped in the following 4 weeks. The number of skydives women performed during pregnancy ranged from 2 up to 200; 15 of the participants had less than 11 jumps, and another 14 had 11 to 50 jumps during pregnancy. Ten participants jumped between 51 and 150 times and 4 more than 150 times. Fourteen participants did not answer this question. Respondents restricted their skydiving activity to “blue skies” (n = 14), “slower parachute” (n = 9), “Taking it easier” (n = 6), “special aircraft exit” (n = 1), “Special packing” (n = 1) or “Team jumps only” (n = 1), and/or “no wind” conditions (n = 7). In Figure 1, the gestational age (GA) of stopping the sport are given. Eight participants described pregnancy-related problems: 3 had hypertension, 2 diabetes, and 1 preterm labor, 1 preeclampsia, and 1 placenta praevia. Thirty-one skydivers delivered beyond 35 weeks GA (Figure 2); 24 had vaginal deliveries, 5 had a planned caesarean section, and 8 had an unplanned caesarean section. Five had a continuing pregnancy at the time of the questionnaire. Women were asked when they resumed skydiving after delivery; 6 started within 6 weeks, 20 resumed within 6 weeks to 6 months, 23 returned within 6 months to 1 year, and only 1 waited more than a year. Seven women responded “not yet” with no recorded time since delivery. Forty-one responded to who supported the mother-to-be in her decision to continue to skydive; in 27 cases, a supportive partner, followed by doctors (n = 8), other skydivers (n = 4), and midwives (n = 2). The 19 free text answers can be classified in the following categories: 5 replies were about stopping because of “(pregnancy)-hormone”–related issues, a further 5 about the “safety measures” taken/rules about returning to skydive, 4 encouraged the questionnaire/research, 3 explained the support from doctors/midwives and work colleagues, 1 stated the time in the wind-tunnel, and 1 gave the start of the pregnancy.
Systematic Literature Review
The results of the search items were “skydive” or “parachute” (646 results), “parachute” or “skydive,” and www.cjsportmed.com |
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pregnancy or at least very careful decision making. The recommendation of further national parachuting associations is “don’t jump during pregnancy.”30–32 Additional to these recommendations, drop zone guidelines for parachutists generally do not allow skydivers to board the drop-off plane if feeling unwell/unfit.
Epidemiology
FIGURE 1. Number of participants and the GA of stopping parachuting.
“pregnancy” (24 results). None of these were relevant to the question of this article. In detail, 12 of the results contained the word parachute/skydive metaphorically that is in the meaning of emergency technique or “parachute like mitral valve.”4–15 A further 9 articles were dealing with hyperarousal or stress-related hormones as a response to skydiving,16–24 1 article was about dietary restrictions in pregnant women,25 1 was a case report of a failure of a transtibial prosthesis during freefall,26 and 1 case series investigated the time distortion in skydivers.27 To the best of our knowledge, there is no medical literature available regarding pregnant skydivers.
DISCUSSION Recommendations Regarding Parachuting and Pregnancy The limited available medical knowledge is reflected in different rules regarding the fitness to jump in different countries. The technical and safety committee of the Federation Aeronautique International (FAI), as the governing body, addressed this in a report in 2009, describing the differences of the participating 24 nations regarding medical certificates. The issue of pregnant skydivers was not addressed.2 The Australian parachuting association provides an article about pregnancy and skydiving by Leanne Critchley.28 The German parachuting federation provides a brief review of the possible risks.29 Both recommend not jumping during
FIGURE 2. Number of participants and GA at the time of delivery.
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Comparing our participants with the average USPA member, they were 10 years younger,1 and the age distribution shows that skydiving is an activity for all age groups of reproductive women. It also shows that skydivers in their first pregnancy were dominant in our study. This may be because of the changed interests/lifestyle once a baby is born.
Pregnancy Physiology About 75% of expecting mothers experience nausea and/or vomiting in early pregnancy. In half of these patients, this condition is so severe that work time is lost, or family relations are affected.33 Vomiting during freefall is a known problem for first time skydivers (tandem guests). For regular skydivers, common sense and drop zone rules recommend no jumping when feeling nauseous. During the first trimester of pregnancy, the development of all essential organs is initiated. In the second trimester, fetal organs become fully functional, and in the third trimester, the fetus matures and grows. Considering an average weight gain of 11 kg and growth of a pregnant abdomen, the center of gravity moves forward, resulting in different flight behavior as the pregnancy advances. The reported pregnancy-related medical conditions are not known to be caused by skydiving. The reasons for stopping skydiving were not investigated; they may be because of the physical changes and different “flight” behavior or illfitting parachute equipment or because of a change in perceived risk.
Ascent of the Skydive Skydiving starts with the boarding of the drop-off plane. It takes the skydiver to exit altitude in minutes. The most common exit height in recreational skydiving is about 3000 to 4500 m above ground level (AGL). The effect of altitude on pregnancy outcome has been studied in several trials on various parameters. Physiological O2 saturation is not compromised up to 3000 m above sea level (ASL) in healthy humans.34 From there, the hemoglobin saturation slowly decreases to the “death zone” at 7500 m. The drop altitude of a recreational skydive is usually about 3000 to 4500 m AGL. The skydiver’s ascent takes up to 25 minutes, depending on the type of aircraft. This results in a short-term hypoxia with an ;85% hemoglobin O2 saturation;35 therefore, parachuting guidelines regulate the oxygen supply in drop-off planes. In comparison, in civilian passenger flights, the cabin pressure simulates an altitude of 2000 m ASL. Humans can adapt to higher altitude conditions. Shortterm stays at 2500 m ASL seem to have no negative effects on the fetus.36,37 However, total and villous placental volumes were reduced in non-native women living at an altitude of 3100 m ASL compared with women living at low altitude.38 Ó 2014 Lippincott Williams & Wilkins
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Caniggia et al39 showed the influence of reduced O2 saturation (3%) in the first weeks of gestation on trophoblast differentiation; the observed changes were similar to the changes found in pre-eclamptic placentas. In the third trimester, Postigo et al40 compared pregnancy and fetal outcome in European and Andean mothers in relation to the altitude of their homes (400 vs 3600 m ASL). The authors found an altitude-related decrease in fetal birth weight in both groups. Also, fetuses exposed to lower maternal blood oxygen saturation extracted a significantly higher proportion of oxygen from the maternal system. These adaptations resulted in similar fetal oxygen delivery and consumption across all 4 groups. Polvi et al41 looked at the hemodynamic effects of maternal hypo-oxygenation and hyper-oxygenation. They exposed 10 term mothers to 10% oxygen saturation and monitored maternal and fetal parameters. The authors found a redistribution of maternal blood (maternal internal carotid artery and uterine artery) but could not find an effect on the fetus in the baseline fetal heart rate, heart rate variability, or Doppler velocimetry in the umbilical artery and the middle cerebral artery. The GA of the patients of this study ranged from 35 to 41 weeks. These studies are relevant for participants staying long-term at high altitudes. Thus far, no medical data exist that show negative effects of short-term hypoxia in pregnancy, as experienced by skydivers, but there is strong in vitro data that fetal cells are influenced by reduced O2 saturation.
Freefall Descent After exiting the plane, the skydiver freefalls toward earth. The physics of skydiving can be separated into 3 different parts: the freefall, descent under the canopy (including the deceleration during the canopy opening), and landing. With the exit of the airplane, the skydiver accelerates with the gravitational force toward earth. At the moment, the speed record is 587 km/h;42 the “normal” speed for recreational skydivers is between 180 and 280 km/h under 1g of gravitational acceleration.43,44 The speed can be influenced with different jump/wingsuits and body positions. By changing the body surface in the relative wind, the skydiver can accelerate and decelerate or initiate rotations around all 3 body axes. The freefall period is about 35 to 45 seconds depending on the exit altitude and velocity.43,44 Depending on the experience of the skydiver, the regulations allow opening altitudes down to 600 m AGL.31,32 The experience of our participants was comparable with the average USPA member.1 This may represent a bias because of the method of circulation of the survey through professional bodies of the sport or may be an accurate representation of a pregnant skydiving woman’s experience. It is plausible to think less experienced women would be less interested or more conservative in continuing to jump once pregnant. In addition to skydiving experience, canopy size and the packing of the parachute also influence deceleration.
Canopy Opening Opening happens over 2 to 5 seconds; with the opening of the parachute, the skydivers body position swings into an upright position, and the deceleration acts through the axis of Ó 2014 Lippincott Williams & Wilkins
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the body. The canopy opening shock has been studied and presented by the Parks College Parachute Research Group.45 The authors give average opening shocks between 3 and 6g and have also documented hard openings of 9 to 12g. Although the forces during the opening of the parachute are comparable with those during car accidents, the physics (ie, body position and direction of accelerations) are different. A car crashing at 30 km/h into a concrete wall with a 50-cm crumple zone decelerates at 7g. Several articles have been published on pregnancies and car accidents/traumas.46–51 In pregnancy, sudden accelerations and decelerations are postulated to cause rupture of membranes, contractions/preterm labor, or placental abruptions.48,50,51 A complete placental abruption is an obstetric emergency, which demands immediate medical intervention. Needless to say, 600 to 1200 m AGL is not the preferred place for this complication to occur.
Landing Once the parachute or canopy is opened, vertical speed reduces to ;5 m/s (18 km/h) for the landing. The following descent to earth takes 2 to 5 minutes. Modern parachutes (Ram air wing parachutes) work similar to paragliders, converting the vertical speed into a forward momentum, thus resulting in nearly no vertical drop for the landing but creating a forward movement of 20 to over 130 km/h. Fast landing maneuvers are called swooping.43 The horizontal and vertical landing speed can be controlled by steering the parachute. Experienced skydivers can land “on the dot” without forward or downward motion. Misjudging the landing speed/height is a major cause for landing accidents.2 Most accidents happen during the actual landing with a low fatality rate.2 Serious crashes result in major traumas; more common landing injuries include twisted or sprained joints (knees and ankles). Even if the gradual physiological changes of the body are anticipated during second and third trimester, a pregnant woman has an increased risk for major traumas even in a normal lifestyle.52 Schiff53 showed that hospitalization for a fall resulted in “a 4.4-fold increased risk of preterm labor and an 8.0-fold increased risk of placental abruption.” The majority of injuries were fractures to the lower limb. About 79.3% of the patients were in the last trimester. “Acute traumatic injuries in pregnancy are a significant contributor to maternal and fetal morbidity and mortality.”48 Professional bodies (RCOG54, DGGG55, ACOG56) encourage continuing sports at a moderate level but “Women are cautioned about the potential for loss of balance and fetal trauma.,”54 or should consider the risks and benefits very carefully,55 or “Those activities with a high risk of falling or for abdominal trauma should be avoided during pregnancy.”56 Thus, suggesting skydiving in pregnancy is not recommended. To minimize the risk of trauma, our participants did change their jumping habits, for example, “slower” parachute. This refers to the vertical speed after the opening of the parachute and is also normally associated with a longer opening, resulting in a smaller deceleration. Commonly a “slower parachute” is also more voluminous when packed and therefore restricts the physical moves during freefall, resulting in a less www.cjsportmed.com |
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acrobatic dive. A further 7 participants admitted to “more conservative jumping” during pregnancy. This answer can include weather conditions, airplane exit speed, free-flight time, body positions, and also parachute size/packing or type of jumps.
Additional Considerations In addition to the physical forces experienced, the body also releases catecholamines during skydiving. Their effects have been studied on 43 inexperienced tandem skydivers by continuous blood samples 2 hours before the jump to 1 hour after the jump. 57 The results showed a significant cross-correlation for epinephrine and norepinephrine. However, Richter et al 57 also noted “even in a very homogeneous group of subjects and under well-controlled conditions, endocrine responses to acute psychological stress show considerable variations.” Similar results were found in a Finnish study by Hynynen et al.58 They showed that the heart rate of novice and experienced skydivers does not differ during the night or morning before the jump compared with a control day. The study did find slightly elevated adrenalin secretion in the nights before the jump in comparison with the control nights. The authors conclude that the parachute jump, as an acute highly stressful event, had no anticipatory effect on autonomic modulation of the heart, although both the novices and experienced jumpers had markedly accentuated sympathetic activation during the parachuting. As the effects of occasional stress on the pregnancy are not yet fully understood, it is very hard to predict the influence of stress caused by skydiving for the pregnancy.40,59 Stress in general and other environmental factors might contribute to the “fetal programming hypothesis,” which has been discussed first in the 1970s,60 and several publications contribute to this hypothesis.61,62
Obstetrical Outcome Depending on the obstetric management, some of the given complications may have been a reason for an early or surgical delivery. Due to the low number, these figures do not allow interpretation of the effect of skydiving on delivery outcome, but the mode and the GA of delivery seem not to be affected by skydiving. Generally, the survey results show that the majority of skydivers did try to reduce the risk of injuries as much as possible. This indicates an active decision to continue skydiving during pregnancy. Participants did involve medical professionals in the decision, but the decision was more often based on the partner’s support and/or advice given from fellow skydivers.
Limitations The study limitations are the low participating number and the impossibility to verify the answers with medical notes. The data therefore lack the potential to answer further questions or give further details. There are to date, however, no published studies on skydiving in pregnancy; this study therefore adds to the available information for both women and their carers. Despite the
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discussed and well-known risks of skydiving during pregnancy, more experienced skydivers actively decide to continue to jump during their pregnancy. The possible risks of fatalities during pregnancy, especially in high-risk activities, are accepted by the athletes. The participants seem to have modified their skydiving behaviors to reduce the known risk; however, in view of the lack of research in this area, the actual risk profile is unknown.
CONCLUSIONS
As a medical professional, the recommendation “don’t jump during pregnancy” is undoubtedly the safest approach for mother and child. Further research into the risks of skydiving in pregnancy among the population of women not taking this advice would be beneficial. A possible lesser risk alternative to skydiving could be wind-tunnel training.
ACKNOWLEDGMENTS The authors thank Prof Hans-Helmut Thiele from the German Parachuting Association for his support in promoting the study internationally and professional comments. Also, the authors thank Ronald Overdijk and Liam McNulty from the International Parachuting Commission (IPC) for being supportive toward the study, and all the participants for their time and honesty. REFERENCES 1. United States Parachute Association. Membership survey. 2011. www. uspa.org/Portals/0/MembershipSurveys/memsurvey10.pdf. Accessed August 20, 2012. 2. FAI/IPC. IPC safety survey report 2010. 2011. issuu.com/delta3x/docs/ safety_report_2010. Accessed August 10, 2012. 3. Shah A, Cook C, Pietrobon R. Suggested guidelines for reporting results of web-based surveys in the archives. Arch Surg. 2007;142:1110; author reply 1110. 4. Smith MM, Murray J. Parachute without a ripcord: the skydive of communication interaction. Augment Altern Commun. 2011;27: 292–303. 5. Purvis J, Sharma D. Adult parachute mitral valve detected in pregnancy. Heart. 2011;97:1192. 6. Dikecligil GN, Mujica-Parodi LR. Ambulatory and challenge-associated heart rate variability measures predict cardiac responses to real-world acute emotional stress. Biol Psychiatry. 2010;67:1185–1190. 7. D’Aloia A, Vizzardi E, Chiari E, et al. Dynamic mild subaortic left ventricular obstruction caused by an accessory mitral valve attached to the anterior mitral valve in a young pregnant woman. Eur J Echocardiogr. 2008;9:160–161. 8. Zucker N, Levitas A, Zalzstein E. Prenatal diagnosis of Shone’s syndrome: parental counseling and clinical outcome. Ultrasound Obstet Gynecol. 2004;24:629–632. 9. McDermott KB, Jones TC, Petersen SE, et al. Retrieval success is accompanied by enhanced activation in anterior prefrontal cortex during recognition memory: an event-related fMRI study. J Cogn Neurosci. 2000; 12:965–976. 10. Oosthoek PW, Wenink AC, Wisse LJ, et al. Development of the papillary muscles of the mitral valve: morphogenetic background of parachute-like asymmetric mitral valves and other mitral valve anomalies. J Thorac Cardiovasc Surg. 1998;116:36–46. 11. Barau G, Boitouzet V, Bulwa S, et al. Late cerclage. J Gynecol Obstet Biol Reprod (Paris). 1990;19:337–341. 12. Jones SA, Gazzaniga AB, Keller TB. The serosal patch. A surgical parachute. Am J Surg. 1973;126:186–196.
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13. Pesonen E, Haavisto H, Ammälä P, et al. Intrauterine hydrops caused by premature closure of the foramen ovale. Arch Dis Child. 1983;58: 1015–1016. 14. Rodin AE, Singla P. Anomalous coronary artery simulating parachute mitral valve. Am J Clin Pathol. 1984;82:622–624. 15. Benacerraf BR, Saltzman DH, Sanders SP. Sonographic sign suggesting the prenatal diagnosis of coarctation of the aorta. J Ultrasound Med. 1989;8:65–69. 16. Sterlini GL, Bryant RA. Hyperarousal and dissociation: a study of novice skydivers. Behav Res Ther. 2002;40:431–437. 17. Thatcher J, Reeves S, Dorling D, et al. Motivation, stress, and cortisol responses in skydiving. Percept Mot Skills. 2003;97:995–1002. 18. Cavenett T, Nixon RDV. The effect of arousal on memory for emotionally-relevant information: a study of skydivers. Behav Res Ther. 2006;44:1461–1469. 19. Gutovitz S, Weber K, Kaciuban S, et al. Middle ear pressure and symptoms after skydiving. Aviat Space Environ Med. 2008;79:533–536. 20. Woodman T, Cazenave N, Le Scanff C. Skydiving as emotion regulation: the rise and fall of anxiety is moderated by alexithymia. J Sport Exerc Psychol. 2008;30:424–433. 21. Woodman T, Huggins M, Le Scanff C, et al. Alexithymia determines the anxiety experienced in skydiving. J Affect Disord. 2009;116:134–138. 22. Mujica-Parodi LR, Renelique R, Taylor MK. Higher body fat percentage is associated with increased cortisol reactivity and impaired cognitive resilience in response to acute emotional stress. Int J Obes (Lond). 2009;33:157–165. 23. DeDora DJ, Carlson JM, Mujica-Parodi LR. Acute stress eliminates female advantage in detection of ambiguous negative affect. Evol Psychol. 2011;9:532–542. 24. Rubin D, Botanov Y, Hajcak G, et al. Second-hand stress: inhalation of stress sweat enhances neural response to neutral faces. Soc Cogn Affect Neurosci. 2012;7:208–212. 25. Duckett JR. Guidelines for dietary supplementation of pregnant women in a Rwandan refugee camp. J R Army Med Corps. 1996;142:13–14. 26. Gordon AT, Land RM. Transtibial prosthesis suspension failure during skydiving freefall: a case report. Assist Technol. 2009;21:25–27. 27. Campbell LA, Bryant RA. How time flies: a study of novice skydivers. Behav Res Ther. 2007;45:1389–1392. 28. Federation AP. Skydive and pregnancy. 2012. www.apf.asn.au/ ArticleDocuments/145/Skydiving_and_Pregnancy.pdf.aspx. Accessed August 15, 2012. 29. Fallschirmsportverband D. Schwangerschaft und fallschrimspringen. 2010. www.dfv.aero/files/service/Schwangerschaft_und_Fallschirmspringen.pdf. Accessed August 20, 2012. 30. British Parachuting Association. Declaration of fitness to parachute. 2011. www.bpa.org.uk/forms/download/104/pdf. Accessed November 4, 2011. 31. Fallschirmsportverband D. Tauglichkeitsuntersuchung. 2011. www.metatag. de/webs/dfv/downloads/Tauglichkeitsuntersuchung_für_Fallschirmspringer_ 07-2003.pdf. Accessed November 4, 2011. 32. United States Parachute Association. Basic safety requirements. 2011. www.uspa.org/SIM/Read/Section2/tabid/164/Default.aspx#21c. Accessed November 4, 2011. 33. Niebyl JR. Clinical practice. Nausea and vomiting in pregnancy. N Engl J Med. 2010;363:1544–1550. 34. Burtscher M, Mairer K, Wille M, et al. Short-term exposure to hypoxia for work and leisure activities in health and disease: which level of hypoxia is safe? Sleep Breath. 2012;16:435–442. 35. Harding MR. Pressure changes and hypoxia in aviation. In: Pandolf KB, Burr RB, eds. Medical Aspects of Harsh Environments. Washington D.C.: Borden Institute, Office of the Surgeon General, US Army Medical Department; 2002:990. 36. Baumann H, Huch R. Altitude exposure and staying at high altitude in pregnancy: effects on the mother and fetus [in German]. Zentralbl Gynakol. 1986;108:889–899. 37. Huch R. Physical activity at altitude in pregnancy. Semin Perinatol. 1996;20:303–314.
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38. Van Patot MCT, Valdez M, Becky V, et al. Impact of pregnancy at high altitude on placental morphology in non-native women with and without preeclampsia. Placenta. 2009;30:523–528. 39. Caniggia I, Winter J, Lye SJ, et al. Oxygen and placental development during the first trimester: implications for the pathophysiology of preeclampsia. Placenta. 2000;21 (suppl A):S25–S30. 40. Postigo L, Heredia G, Illsley NP, et al. Where the O2 goes to: preservation of human fetal oxygen delivery and consumption at high altitude. J Physiol. 2009;587:693–708. 41. Polvi HJ, Pirhonen JP, Erkkola RU. The hemodynamic effects of maternal hypo- and hyperoxygenation in healthy term pregnancies. Obstet Gynecol. 1995;86:795–799. 42. FAI. Baumgaertner breaks the maximum vertical speed world record. 2012. www.fai.org/ipc-slider-news/36077-baumgartner-breaks-the-maximumvertical-speed-world-record. Accessed August 8, 2012. 43. Germain B. Landings, high speed approaches and landings. In: Germain B, ed. The Parachute and Its Pilot: The Ultimate Guide for the RAM-Air Aviator. New York, NY: American Printing; 2004:64–111. 44. Poynter D, Turoff M. Chapter one: jump? Out of an airplane? In: Poynter D, Turoff M, eds. Parachuting: The Skydivers Handbook. Santa Barbara, CA: ParaPublishing; 2007. 45. Ptovin J, Potvin G. Parachute opening shock basics. Paper presented at: Parachute Industry Association Symposium, January 30, 2001; San Diego, MO. www.pcprg.com/s01out.htm. Accessed August 12, 2013. 46. Aitokallio-Tallberg A, Halmesmäki E. Motor vehicle accident during the second or third trimester of pregnancy. Acta Obstet Gynecol Scand. 1997;76:313–317. 47. Aniuliene R, Proseviciute L, Aniulis P, Pamerneckas A. N_esciųjų trauma: komplikacijos, baigtys, gydymas. Medicina (Kaunas). 2006;42: 586–591. 48. Brown HL. Trauma in pregnancy. Obstet Gynecol. 2009;114:147–160. 49. El Kady D, Gilbert WM, Xing G, et al. Association of maternal fractures with adverse perinatal outcomes. Am J Obstet Gynecol. 2006;195: 711–716. 50. Fischer PE, Zarzaur BL, Fabian TC, et al. Minor trauma is an unrecognized contributor to poor fetal outcomes: a population-based study of 78,552 pregnancies. J Trauma. 2011;71:90–93. 51. Melamed N, Aviram A, Silver M, et al. Pregnancy course and outcome following blunt trauma. J Matern Fetal Neonatal Med. 2012;25:1612–1617. 52. Redelmeier DA, Drucker A, Venkatesh V. Major trauma in pregnant women during the summer. J Trauma. 2005;59:112–116. 53. Schiff MA. Pregnancy outcomes following hospitalisation for a fall in Washington State from 1987 to 2004. BJOG. 2008;115:1648–1654. 54. Royal College of Obstetrics and Gynaecology. Exercise in pregnancy. RCOG Statement. 2012;4:1–7. 55. Korsten-Reck U. Schwangerschaft und Sport. Gynäkologe. 2011;44:847–853. 56. American College of Obstetricians and Gynecologists. Exercise during pregnancy and the postpartum period. Clin Obstet Gynecol. 2003;46: 496–499. 57. Richter SD, Schürmeyer TH, Schedlowski M, et al. Time kinetics of the endocrine response to acute psychological stress. J Clin Endocrinol Metab. 1996;81:1956–1960. 58. Hynynen E, Konttinen N, Rusko H. Heart rate variability and stress hormones in novice and experienced parachutists anticipating a jump. Aviat Space Environ Med. 2009;80:976–980. 59. Li J, Olsen J, Vestergaard M, et al. Prenatal stress exposure related to maternal bereavement and risk of childhood overweight. PLoS One. 2010;5:e11896. 60. Gardiner HM. Intrauterine programming of the cardiovascular system. Ultrasound Obstet Gynecol. 2008;32:481–484. 61. Forsdahl A. Are poor living conditions in childhood and adolescence an important risk factor for arteriosclerotic heart disease? Br J Prev Soc Med. 1977;31:91–95. 62. Rothenberger SE, Resch F, Doszpod N, et al. Prenatal stress and infant affective reactivity at five months of age. Early Hum Dev. 2011;87: 129–136.
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Parachuting and Pregnancy: What Do We Know About Pregnant Skydivers and the Risks They Are Taking? Florian Ebner, MD,* Achim Wöckel, PhD,* Wolfgang Janni, PhD,* and Helen Paterson, MMedSc†
Objective: There is little medical knowledge about the risks of
antenatal programming, or short-term hypoxia and pregnancy outcome in pregnant skydiving women and their offspring.
skydiving during pregnancy. Some national parachuting associations ask for a doctor’s permission; others recommend not jumping at all during pregnancy. This article provides survey data and a literature review of pregnancy and parachuting/skydiving related issues to help the pregnant skydiver and her obstetrician make an informed decision. Survey data presented include pregnancy, delivery, and parachuting information from skydivers who jumped during pregnancy.
Conclusions: Pregnancy itself is a risk factor for injuries. Injuries in pregnancy are clearly associated with an unfavorable pregnancy outcome. The recommendation “do not skydive during pregnancy” is the safest approach. A possible lesser risk alternative to skydiving could be wind-tunnel training.
Design: International retrospective anonymous online questionnaire considering the Checklist for Reporting Results of Internet E-Surveys (CHERRIE). The PubMed database was searched with using the terms “skydive,” “pregnancy,” and “parachute” (query April 2013).
Setting: Web page questionnaire on skydivers’ epidemiology, experience, and pregnancy-related information. Participants: Fifty-seven parous female skydivers. Assessment of Risk Factors: Information on athletes’ experience, weather conditions, obstetric history (gravida, gestational week), delivery mode was obtained. Main Outcome Measures: Epidemiology of pregnant skydivers and literature review to provide information on skydiving risks. Results: Women do actively decide to skydive while pregnant. The majority of our participants were between 25-year-old and 35-yearold primips with 100 to 1000 jumps experience, answering the questionnaire from a European IP address. Precautions are taken in terms of weather conditions, gear, or sports partner. The literature review found no relevant literature regarding the question. Literature is searched for risk factors that come close to the ones in skydiving (ie, oxygen saturation, shock forces, and others). Further studies are needed to show the long-term effect of stress or low O2 saturation on
Submitted for publication June 3, 2013; accepted December 6, 2013. From the *Abteilung für Frauenheilkunde, Universitätsklinik Ulm, Ulm, Germany; and †Department of Women’s Health, Dunedin Hospital, Otago University, Otago, New Zealand. The authors report no conflicts of interest. F. Ebner initiated the study, made the connection to the parachuting associations, and wrote the article. H. Paterson contributed to the questionnaire and reviewed the article. W. Janni and A. Wöckel reviewed the article. All researchers had full access to all of the data. Corresponding Author: Florian Ebner, MD, Abteilung für Frauenheilkunde, Universitätsklinik Ulm, Prittwitzstr, 43, Ulm 89075, Germany (dr.ebner@ web.de). Copyright © 2014 by Lippincott Williams & Wilkins
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Clinical Relevance: This article provides insights into the pregnant skydiver’s decision making regarding the sports. In combination with the literature review, we provide up-to-date easy to understand information on the possible risk factors. This is a valuable source of information for the care providers of female skydivers to understand and compare the risk factors of this sport. With this information, the professional recommendation and relationship are strengthened. This article also guides the need for further research. Possible research areas include pregnancy and sports-related risk factors, placentation and prenatal programming, physical and psychological factors associated with skydiving. Key Words: pregnancy, skydive, parachute, skydiving, pregnant, sport, hypoxia, risk, delivery, altitude (Clin J Sport Med 2014;24:468–473)
INTRODUCTION Extreme sports are becoming more common. It can be challenging for doctors and health care professionals to be consulted for advice by an extreme sports practitioner, such as a recreational parachutist (skydiver). According to the United States Parachuting Association (USPA), the average skydiver is male, aged 31 to 39 years and has 26 to 500 jumps. They report 97.5% of participants are injury free, and only 28% have attended the USPA security day.1 Depending on the situation (weather, financial), skydivers can make 10+ jumps a day. The 2010 safety report of the International Parachuting commission (IPC) technical and safety commission states a fatality rate of 1 in 97 000 jumps. The 2 leading categories for fatalities were landing errors or fast canopies/intentional fast landing.2 There is little medical knowledge about the risks of skydiving during pregnancy. General risk factors for skydivers include low oxygen saturation at high altitudes and mechanical forces during canopy opening or landing. This article aims to give basic information about leisure parachuting (skydiving) and assess possible risks for pregnant Clin J Sport Med Volume 24, Number 6, November 2014
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athletes; therefore, the skydiving behavior and adaptations made by pregnant skydivers are investigated. This information will help pregnant skydivers and their obstetricians to make an informed decision.
METHODS An anonymous online survey was developed consistent with the Checklist for Reporting Results of Internet E-Surveys (CHERRIE) guidelines (Table 1) for female skydivers with experience of skydiving during pregnancy.3 The link was sent out to the International Parachuting Commission (FAI/IPC) and national parachuting federations directly. This included 9 of the top 11 federations in terms of membership and jump numbers (IPC). 2 Additionally, it was posted in online discussion forums on skydiving and pregnancy. One of the authors (F.E.) has been judging skydiving events internationally for 10 years; therefore, the survey was also sent to skydivers known to him to disseminate. The survey asked for basic obstetric information to get an overview of the obstetric situation. We included a question on pregnancy complications but deliberately did not ask for details of adverse pregnancy outcomes or information on the child’s development, as this might have led to a participation bias. Also, we were interested in the experience of the skydiver and the security measures taken. During pregnancy, most women seek professional and semiprofessional advice. Therefore, we asked who supported them in their decision to continue skydiving. Ethics were granted by the University of Heidelberg Ethics Commission under the trial registration no. S-436/2011.
Systematic Literature Review The National Library of Medicine (PubMed) was queried for the search terms “skydive,” “pregnancy,” and “parachute” without restrictions regarding date, journal, or language. The literature results were reviewed regarding relevance.
TABLE 1. Survey Questions How old were you at the beginning of the pregnancy?* Was this your first/second/third pregnancy? How many skydives did you have before the pregnancy and how many skydives did you do during the pregnancy (including those when you could possibly be not aware of the pregnancy)?* Roughly when did you stop skydiving during your pregnancy? (Normal pregnancy is 40 wk)* What other circumstances did you consider to increase the safety? Were there any complications during the pregnancy? When and how did you deliver?* When did/do you go skydiving again? Who supported you in your decision to continue to skydive? Do you have any other comments that you feel could add value? *Obligatory questions.
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RESULTS Survey The questionnaire page was visited 62 times; 57 questionnaires were completed between September and November 2010. The questionnaire was answered from IP addresses around the world. The majority of participants logged in from Europe with Germany (n = 16), Finland (n = 12), England (n = 4), Italy and Netherlands (each n = 2), and Austria, Slovenia, and Switzerland (each n = 1). The USA and Australia (each n = 6) and New Zealand (n = 3), Brazil, Russia, and South Africa (each n = 1) added to the poll. Twenty-three participants were aged between 25 and 30 years, 16 aged between 31 and 35, and 15 participants aged over 35. Only 3 participants were under 25. Forty-six participants were primiparous. Only 3 of the participants had less than 100 jumps before pregnancy, 25 had 100 to 500 jumps, 11 had 500 to 1000 jumps, 5 had 1000 to 2000 jumps, and 12 had more than 2000 jumps. Twenty-one participants stopped parachuting in the first trimester, and a further 13 stopped in the following 4 weeks. The number of skydives women performed during pregnancy ranged from 2 up to 200; 15 of the participants had less than 11 jumps, and another 14 had 11 to 50 jumps during pregnancy. Ten participants jumped between 51 and 150 times and 4 more than 150 times. Fourteen participants did not answer this question. Respondents restricted their skydiving activity to “blue skies” (n = 14), “slower parachute” (n = 9), “Taking it easier” (n = 6), “special aircraft exit” (n = 1), “Special packing” (n = 1) or “Team jumps only” (n = 1), and/or “no wind” conditions (n = 7). In Figure 1, the gestational age (GA) of stopping the sport are given. Eight participants described pregnancy-related problems: 3 had hypertension, 2 diabetes, and 1 preterm labor, 1 preeclampsia, and 1 placenta praevia. Thirty-one skydivers delivered beyond 35 weeks GA (Figure 2); 24 had vaginal deliveries, 5 had a planned caesarean section, and 8 had an unplanned caesarean section. Five had a continuing pregnancy at the time of the questionnaire. Women were asked when they resumed skydiving after delivery; 6 started within 6 weeks, 20 resumed within 6 weeks to 6 months, 23 returned within 6 months to 1 year, and only 1 waited more than a year. Seven women responded “not yet” with no recorded time since delivery. Forty-one responded to who supported the mother-to-be in her decision to continue to skydive; in 27 cases, a supportive partner, followed by doctors (n = 8), other skydivers (n = 4), and midwives (n = 2). The 19 free text answers can be classified in the following categories: 5 replies were about stopping because of “(pregnancy)-hormone”–related issues, a further 5 about the “safety measures” taken/rules about returning to skydive, 4 encouraged the questionnaire/research, 3 explained the support from doctors/midwives and work colleagues, 1 stated the time in the wind-tunnel, and 1 gave the start of the pregnancy.
Systematic Literature Review
The results of the search items were “skydive” or “parachute” (646 results), “parachute” or “skydive,” and www.cjsportmed.com |
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pregnancy or at least very careful decision making. The recommendation of further national parachuting associations is “don’t jump during pregnancy.”30–32 Additional to these recommendations, drop zone guidelines for parachutists generally do not allow skydivers to board the drop-off plane if feeling unwell/unfit.
Epidemiology
FIGURE 1. Number of participants and the GA of stopping parachuting.
“pregnancy” (24 results). None of these were relevant to the question of this article. In detail, 12 of the results contained the word parachute/skydive metaphorically that is in the meaning of emergency technique or “parachute like mitral valve.”4–15 A further 9 articles were dealing with hyperarousal or stress-related hormones as a response to skydiving,16–24 1 article was about dietary restrictions in pregnant women,25 1 was a case report of a failure of a transtibial prosthesis during freefall,26 and 1 case series investigated the time distortion in skydivers.27 To the best of our knowledge, there is no medical literature available regarding pregnant skydivers.
DISCUSSION Recommendations Regarding Parachuting and Pregnancy The limited available medical knowledge is reflected in different rules regarding the fitness to jump in different countries. The technical and safety committee of the Federation Aeronautique International (FAI), as the governing body, addressed this in a report in 2009, describing the differences of the participating 24 nations regarding medical certificates. The issue of pregnant skydivers was not addressed.2 The Australian parachuting association provides an article about pregnancy and skydiving by Leanne Critchley.28 The German parachuting federation provides a brief review of the possible risks.29 Both recommend not jumping during
FIGURE 2. Number of participants and GA at the time of delivery.
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Comparing our participants with the average USPA member, they were 10 years younger,1 and the age distribution shows that skydiving is an activity for all age groups of reproductive women. It also shows that skydivers in their first pregnancy were dominant in our study. This may be because of the changed interests/lifestyle once a baby is born.
Pregnancy Physiology About 75% of expecting mothers experience nausea and/or vomiting in early pregnancy. In half of these patients, this condition is so severe that work time is lost, or family relations are affected.33 Vomiting during freefall is a known problem for first time skydivers (tandem guests). For regular skydivers, common sense and drop zone rules recommend no jumping when feeling nauseous. During the first trimester of pregnancy, the development of all essential organs is initiated. In the second trimester, fetal organs become fully functional, and in the third trimester, the fetus matures and grows. Considering an average weight gain of 11 kg and growth of a pregnant abdomen, the center of gravity moves forward, resulting in different flight behavior as the pregnancy advances. The reported pregnancy-related medical conditions are not known to be caused by skydiving. The reasons for stopping skydiving were not investigated; they may be because of the physical changes and different “flight” behavior or illfitting parachute equipment or because of a change in perceived risk.
Ascent of the Skydive Skydiving starts with the boarding of the drop-off plane. It takes the skydiver to exit altitude in minutes. The most common exit height in recreational skydiving is about 3000 to 4500 m above ground level (AGL). The effect of altitude on pregnancy outcome has been studied in several trials on various parameters. Physiological O2 saturation is not compromised up to 3000 m above sea level (ASL) in healthy humans.34 From there, the hemoglobin saturation slowly decreases to the “death zone” at 7500 m. The drop altitude of a recreational skydive is usually about 3000 to 4500 m AGL. The skydiver’s ascent takes up to 25 minutes, depending on the type of aircraft. This results in a short-term hypoxia with an ;85% hemoglobin O2 saturation;35 therefore, parachuting guidelines regulate the oxygen supply in drop-off planes. In comparison, in civilian passenger flights, the cabin pressure simulates an altitude of 2000 m ASL. Humans can adapt to higher altitude conditions. Shortterm stays at 2500 m ASL seem to have no negative effects on the fetus.36,37 However, total and villous placental volumes were reduced in non-native women living at an altitude of 3100 m ASL compared with women living at low altitude.38 Ó 2014 Lippincott Williams & Wilkins
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Caniggia et al39 showed the influence of reduced O2 saturation (3%) in the first weeks of gestation on trophoblast differentiation; the observed changes were similar to the changes found in pre-eclamptic placentas. In the third trimester, Postigo et al40 compared pregnancy and fetal outcome in European and Andean mothers in relation to the altitude of their homes (400 vs 3600 m ASL). The authors found an altitude-related decrease in fetal birth weight in both groups. Also, fetuses exposed to lower maternal blood oxygen saturation extracted a significantly higher proportion of oxygen from the maternal system. These adaptations resulted in similar fetal oxygen delivery and consumption across all 4 groups. Polvi et al41 looked at the hemodynamic effects of maternal hypo-oxygenation and hyper-oxygenation. They exposed 10 term mothers to 10% oxygen saturation and monitored maternal and fetal parameters. The authors found a redistribution of maternal blood (maternal internal carotid artery and uterine artery) but could not find an effect on the fetus in the baseline fetal heart rate, heart rate variability, or Doppler velocimetry in the umbilical artery and the middle cerebral artery. The GA of the patients of this study ranged from 35 to 41 weeks. These studies are relevant for participants staying long-term at high altitudes. Thus far, no medical data exist that show negative effects of short-term hypoxia in pregnancy, as experienced by skydivers, but there is strong in vitro data that fetal cells are influenced by reduced O2 saturation.
Freefall Descent After exiting the plane, the skydiver freefalls toward earth. The physics of skydiving can be separated into 3 different parts: the freefall, descent under the canopy (including the deceleration during the canopy opening), and landing. With the exit of the airplane, the skydiver accelerates with the gravitational force toward earth. At the moment, the speed record is 587 km/h;42 the “normal” speed for recreational skydivers is between 180 and 280 km/h under 1g of gravitational acceleration.43,44 The speed can be influenced with different jump/wingsuits and body positions. By changing the body surface in the relative wind, the skydiver can accelerate and decelerate or initiate rotations around all 3 body axes. The freefall period is about 35 to 45 seconds depending on the exit altitude and velocity.43,44 Depending on the experience of the skydiver, the regulations allow opening altitudes down to 600 m AGL.31,32 The experience of our participants was comparable with the average USPA member.1 This may represent a bias because of the method of circulation of the survey through professional bodies of the sport or may be an accurate representation of a pregnant skydiving woman’s experience. It is plausible to think less experienced women would be less interested or more conservative in continuing to jump once pregnant. In addition to skydiving experience, canopy size and the packing of the parachute also influence deceleration.
Canopy Opening Opening happens over 2 to 5 seconds; with the opening of the parachute, the skydivers body position swings into an upright position, and the deceleration acts through the axis of Ó 2014 Lippincott Williams & Wilkins
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the body. The canopy opening shock has been studied and presented by the Parks College Parachute Research Group.45 The authors give average opening shocks between 3 and 6g and have also documented hard openings of 9 to 12g. Although the forces during the opening of the parachute are comparable with those during car accidents, the physics (ie, body position and direction of accelerations) are different. A car crashing at 30 km/h into a concrete wall with a 50-cm crumple zone decelerates at 7g. Several articles have been published on pregnancies and car accidents/traumas.46–51 In pregnancy, sudden accelerations and decelerations are postulated to cause rupture of membranes, contractions/preterm labor, or placental abruptions.48,50,51 A complete placental abruption is an obstetric emergency, which demands immediate medical intervention. Needless to say, 600 to 1200 m AGL is not the preferred place for this complication to occur.
Landing Once the parachute or canopy is opened, vertical speed reduces to ;5 m/s (18 km/h) for the landing. The following descent to earth takes 2 to 5 minutes. Modern parachutes (Ram air wing parachutes) work similar to paragliders, converting the vertical speed into a forward momentum, thus resulting in nearly no vertical drop for the landing but creating a forward movement of 20 to over 130 km/h. Fast landing maneuvers are called swooping.43 The horizontal and vertical landing speed can be controlled by steering the parachute. Experienced skydivers can land “on the dot” without forward or downward motion. Misjudging the landing speed/height is a major cause for landing accidents.2 Most accidents happen during the actual landing with a low fatality rate.2 Serious crashes result in major traumas; more common landing injuries include twisted or sprained joints (knees and ankles). Even if the gradual physiological changes of the body are anticipated during second and third trimester, a pregnant woman has an increased risk for major traumas even in a normal lifestyle.52 Schiff53 showed that hospitalization for a fall resulted in “a 4.4-fold increased risk of preterm labor and an 8.0-fold increased risk of placental abruption.” The majority of injuries were fractures to the lower limb. About 79.3% of the patients were in the last trimester. “Acute traumatic injuries in pregnancy are a significant contributor to maternal and fetal morbidity and mortality.”48 Professional bodies (RCOG54, DGGG55, ACOG56) encourage continuing sports at a moderate level but “Women are cautioned about the potential for loss of balance and fetal trauma.,”54 or should consider the risks and benefits very carefully,55 or “Those activities with a high risk of falling or for abdominal trauma should be avoided during pregnancy.”56 Thus, suggesting skydiving in pregnancy is not recommended. To minimize the risk of trauma, our participants did change their jumping habits, for example, “slower” parachute. This refers to the vertical speed after the opening of the parachute and is also normally associated with a longer opening, resulting in a smaller deceleration. Commonly a “slower parachute” is also more voluminous when packed and therefore restricts the physical moves during freefall, resulting in a less www.cjsportmed.com |
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acrobatic dive. A further 7 participants admitted to “more conservative jumping” during pregnancy. This answer can include weather conditions, airplane exit speed, free-flight time, body positions, and also parachute size/packing or type of jumps.
Additional Considerations In addition to the physical forces experienced, the body also releases catecholamines during skydiving. Their effects have been studied on 43 inexperienced tandem skydivers by continuous blood samples 2 hours before the jump to 1 hour after the jump. 57 The results showed a significant cross-correlation for epinephrine and norepinephrine. However, Richter et al 57 also noted “even in a very homogeneous group of subjects and under well-controlled conditions, endocrine responses to acute psychological stress show considerable variations.” Similar results were found in a Finnish study by Hynynen et al.58 They showed that the heart rate of novice and experienced skydivers does not differ during the night or morning before the jump compared with a control day. The study did find slightly elevated adrenalin secretion in the nights before the jump in comparison with the control nights. The authors conclude that the parachute jump, as an acute highly stressful event, had no anticipatory effect on autonomic modulation of the heart, although both the novices and experienced jumpers had markedly accentuated sympathetic activation during the parachuting. As the effects of occasional stress on the pregnancy are not yet fully understood, it is very hard to predict the influence of stress caused by skydiving for the pregnancy.40,59 Stress in general and other environmental factors might contribute to the “fetal programming hypothesis,” which has been discussed first in the 1970s,60 and several publications contribute to this hypothesis.61,62
Obstetrical Outcome Depending on the obstetric management, some of the given complications may have been a reason for an early or surgical delivery. Due to the low number, these figures do not allow interpretation of the effect of skydiving on delivery outcome, but the mode and the GA of delivery seem not to be affected by skydiving. Generally, the survey results show that the majority of skydivers did try to reduce the risk of injuries as much as possible. This indicates an active decision to continue skydiving during pregnancy. Participants did involve medical professionals in the decision, but the decision was more often based on the partner’s support and/or advice given from fellow skydivers.
Limitations The study limitations are the low participating number and the impossibility to verify the answers with medical notes. The data therefore lack the potential to answer further questions or give further details. There are to date, however, no published studies on skydiving in pregnancy; this study therefore adds to the available information for both women and their carers. Despite the
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discussed and well-known risks of skydiving during pregnancy, more experienced skydivers actively decide to continue to jump during their pregnancy. The possible risks of fatalities during pregnancy, especially in high-risk activities, are accepted by the athletes. The participants seem to have modified their skydiving behaviors to reduce the known risk; however, in view of the lack of research in this area, the actual risk profile is unknown.
CONCLUSIONS
As a medical professional, the recommendation “don’t jump during pregnancy” is undoubtedly the safest approach for mother and child. Further research into the risks of skydiving in pregnancy among the population of women not taking this advice would be beneficial. A possible lesser risk alternative to skydiving could be wind-tunnel training.
ACKNOWLEDGMENTS The authors thank Prof Hans-Helmut Thiele from the German Parachuting Association for his support in promoting the study internationally and professional comments. Also, the authors thank Ronald Overdijk and Liam McNulty from the International Parachuting Commission (IPC) for being supportive toward the study, and all the participants for their time and honesty. REFERENCES 1. United States Parachute Association. Membership survey. 2011. www. uspa.org/Portals/0/MembershipSurveys/memsurvey10.pdf. Accessed August 20, 2012. 2. FAI/IPC. IPC safety survey report 2010. 2011. issuu.com/delta3x/docs/ safety_report_2010. Accessed August 10, 2012. 3. Shah A, Cook C, Pietrobon R. Suggested guidelines for reporting results of web-based surveys in the archives. Arch Surg. 2007;142:1110; author reply 1110. 4. Smith MM, Murray J. Parachute without a ripcord: the skydive of communication interaction. Augment Altern Commun. 2011;27: 292–303. 5. Purvis J, Sharma D. Adult parachute mitral valve detected in pregnancy. Heart. 2011;97:1192. 6. Dikecligil GN, Mujica-Parodi LR. Ambulatory and challenge-associated heart rate variability measures predict cardiac responses to real-world acute emotional stress. Biol Psychiatry. 2010;67:1185–1190. 7. D’Aloia A, Vizzardi E, Chiari E, et al. Dynamic mild subaortic left ventricular obstruction caused by an accessory mitral valve attached to the anterior mitral valve in a young pregnant woman. Eur J Echocardiogr. 2008;9:160–161. 8. Zucker N, Levitas A, Zalzstein E. Prenatal diagnosis of Shone’s syndrome: parental counseling and clinical outcome. Ultrasound Obstet Gynecol. 2004;24:629–632. 9. McDermott KB, Jones TC, Petersen SE, et al. Retrieval success is accompanied by enhanced activation in anterior prefrontal cortex during recognition memory: an event-related fMRI study. J Cogn Neurosci. 2000; 12:965–976. 10. Oosthoek PW, Wenink AC, Wisse LJ, et al. Development of the papillary muscles of the mitral valve: morphogenetic background of parachute-like asymmetric mitral valves and other mitral valve anomalies. J Thorac Cardiovasc Surg. 1998;116:36–46. 11. Barau G, Boitouzet V, Bulwa S, et al. Late cerclage. J Gynecol Obstet Biol Reprod (Paris). 1990;19:337–341. 12. Jones SA, Gazzaniga AB, Keller TB. The serosal patch. A surgical parachute. Am J Surg. 1973;126:186–196.
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Skydiving and Pregnancy
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