AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 7, NUMBER 2 April 1990
AMBULATORY UTERINE ACTIVITY MONITORING IN THE POST-HOSPITAL CARE OF PATIENTS WITH PRETERM LABOR Jay D. lams, M.D., Francee E Johnson, R.N., B.S.N., and Richard W. O'Shaughnessy, M.D.
Care of women with preterm labor has been reported by Katz et al1 to be enhanced by use of an electronic uterine contraction monitor. We enrolled 76 women with singleton gestations who had been successfully treated for preterm labor into a prospective randomized trial, assigning subjects in a ratio of 1:2 to a group of 27 receiving education and self-palpation (EP) or to a group of 49 receiving education and an ambulatory monitor (EM). Subjects in both groups received an intensive education session at entry and were contacted frequently (5 days/week in EP and daily in EM) thereafter to report symptoms and frequency of contractions. Physicians were advised to adjust the dosage of oral tocolytic to maintain fewer than four contractions per hour. Rates of recurrent preterm labor and preterm delivery did not differ between the groups. Although the sample size in this study is too small to exclude entirely the possibility of alpha error, our inability to demonstrate a difference suggests that the improvement reported by others in pregnancy outcome associated with use of an electronic ambulatory contraction monitor may be the result of daily attention to symptoms and signs of preterm labor.
Ambulatory uterine activity monitoring has been reported to be a useful adjunct in the care of women who have had preterm labor.J Daily monitoring of the patient's uterine activity may allow the physician to recognize recurrent preterm labor and to determine the most effective dosage or oral tocolytics. Newman et al2 have found that maternal selfpalpation for uterine activity is not reliable when compared with instrumental tocodynamometry, suggesting that outpatient ambulatory tocodynamometry might represent a significant advance in the care of women who have had preterm labor. Katz and colleagues1 acknowledged that "factors such as daily telephone contact, the availability of an open emergency line, and the post-transmission feedback may all have influenced perinatal outcome" in their study. They recommended that additional studies be performed in other patient populations. We therefore designed a prospective randomized trial of ambulatory tocodynamometry compared with self-palpa-
tion of uterine activity in a population of women treated for preterm labor. MATERIAL AND METHODS
We enrolled 76 women with singleton gestations who had been treated successfully for preterm labor with parenteral tocolysis in a study approved by our Human Subjects Review Committee. Informed consent was obtained, and subjects were assigned randomly in a ratio of 1:2 to the self-palpation group, designated EP (education and palpation), and the monitor group, designated group EM (education plus monitor), respectively. A ratio of 1:2 was chosen to allow us to gain as much experience with the monitor as possible. Six of 27 subjects (22%) assigned to group EP were subsequently excluded for failure to adhere to protocol guidelines; three of 49 women assigned to group EM (6%) were similarly
The Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio Supported by the Tokos Medical Corporation and The March of Dimes
170
Copyright © 1990 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
Downloaded by: University of British Columbia. Copyrighted material.
ABSTRACT
AMBULATORY MONITORING IN PRETERM LABOR/lams, Johnson, O'Shaughnessy
to modify therapy and activity level in both groups based on symptoms, palpated or monitored contraction data, and cervical status. They were advised to adjust the dosage of oral tocolytic medication to maintain a contraction frequency of less than four per hour and to continue oral tocolysis through 36 weeks. Recurrent preterm labor was diagnosed for purposes of the study when women were readmitted to the hospital for parenteral tocolytic therapy. Because of the multiple physicians and hospitals involved, we did not have access to the cervical examination findings for all patients, and therefore thought that parenteral tocolysis was the most comparable endpoint. The frequent contact with subjects in both groups allowed the nursing staff to assess compliance by both patient and physician with protocol guidelines and with Tokos Medical Corporation advisories regarding appropriate use of the Term Guard system. All births before 37 completed weeks of gestation were reviewed in detail by the principal investigator with the project nursing staff and the attending physician to determine the etiology of the preterm delivery. Births before 36 completed weeks were defined as preterm.
Downloaded by: University of British Columbia. Copyrighted material.
excluded. This difference is statistically significant (p < 0.05). All subjects in both groups had recently received parenteral tocolysis with intravenous ritodrine, intravenous magnesium sulfate, or subcutaneous terbutaline, and all were discharged from the hospital on oral betamimetic medication. Subjects were recruited from the private, transport, and clinic populations served by The Ohio State University tertiary perinatal center. All subjects in both groups received an intensive 60- to 75-minute initial educational session about the signs and symptoms of preterm labor from the nursing staff at the Columbus Tokos Perinatal Nursing Center. This was accomplished by telephone or, when possible, in person at the time of hospital discharge. Group EP subjects performed self-palpation of uterine activity for 1 hour twice daily and were contacted by the nursing staff to report symptoms and contraction frequency daily on weekdays and, as needed, on weekends. Group EM subjects used the Term Guard (Tokos Medical Corporation, Santa Ana, California) ambulatory uterine activity monitor to record contractions for 1 hour twice daily and were contacted daily by center staff to report symptoms and transmit monitored contraction data. Subjects in both groups were instructed to call the monitoring center if symptoms were noted and were asked to palpate or record uterine activity whenever they noted symptoms or an increase in perceived contraction frequency. Subjects in both groups who noted symptoms or more than four contractions per hour were instructed to contact their physician; in many instances, the nursing staff also contacted the physician directly to report findings. Physicians were free
RESULTS
The course and outcome of pregnancy for each study subject is shown in Figure 1. The overall rate of preterm delivery before 36 weeks was 14.3% (3 of 21) in group EP and 19.6% (9 of 46) in group EM. Among subjects with recurrent preterm labor, 28.6%
OUTCOME OF PREGNANCY EDUCATION a PALPATION
No Recurrence of Preterm Labor 14 ( 6 7 % )
Recurrent Preterm Labor 7 (33 %)
0
EDUCATION S MONITOR
Indicated Preterm Births 0
0
PROM 1 (4.8 %)
2
PTL—»PTD 2 (9.5%)
5
Term Births 18 (86%)
XGA = 36.9 ±1 8 weeks X BW = 2963 ± 4 1 8 gm
No Recurrence of Preterm Labor 29 (73 %)
Recurrent Preterm Labor 17 ( 3 7 % )
0
0
Indicated Preterm Births 0
0
1
1
PROM 4 (8.7 %)
3
5
PTL—»PTD 5 (10.9%)
11
Term Births
13
26
37 (80 %) X GA= 36.9 ± 2 . 8 weeks XBW= 2845 ± 6 3 0 gm
Figure 1. Course and outcome of pregnancy for subjects in group EP and group EM. PROM: prematurely ruptured membranes; PTL: preterm labor; PTD: preterm delivery; Term: 36 completed weeks of gestation; x GA: mean gestational age in weeks; x BW: mean birthweight in grams.
171
(2 of 7) in group EP, and 35.3% (6 of 17) in group EM delivered before 36 weeks. In group EP, the mean birthweight was 2963 ± 418 gm, and the mean gestational age was 36.9 ± 1.8 weeks. In group EM, average birthweight was 2845 ± 630 gm, and the mean gestational age was 36.9 ± 2.8 weeks. These differences are not significant. Oral tocolysis was continued in 19 of 21 group EP subjects until delivery, spontaneous amniorrhexis, or 36 completed weeks of gestation. One group EP subject discontinued oral tocolysis at 34 weeks because of side effects. In another EP subject, oral tocolytics were stopped at 35!/2 weeks at the patient's request. Both patients delivered at 38 weeks. In group EM, 44 of 46 subjects continued oral tocolysis until delivery, spontaneous rupture of membranes, or 36 weeks' gestation. In group EM, oral tocolysis was discontinued at 35 weeks in two subjects at the patient's request. One woman delivered the next day, and the other at 37 weeks. As mentioned previously, there were significantly (p < 0.05) more dropouts or exclusions in group EP subjects (6 of 27, 22%) than in group EM subjects (3 of 49, 6%). The resulting comparison of 21 subjects in group EP to 46 in group EM yields a harmonic mean of 29. This sample size is sufficient to have demonstrated a decrease in the preterm birth rate at 36 weeks from 45% to 15%, as reported by Morrison et al3 in subjects at risk of preterm labor. It is not large enough to exclude a fall in preterm delivery from 33% to 15% as reported by Katz et al1 in subjects with preterm labor in the current pregnancy, assuming a power of 0.8 and an alpha of 0.05. We would have liked to enroll more patients to achieve greater statistical power, but thought it best to discontinue this trial simultaneously with a concurrently run companion trial enrolling subjects at risk who had not had preterm labor.4 When that trial was closed after reaching the desired sample size, referring physicians became confused over which subjects were eligible for entry and which were not. The resulting uncertainty led to our decision to stop this trial at the same time. DISCUSSION
There are several possible conclusions that might be drawn from the data presented. The first is simply that our sample size is insufficient to demonstrate a difference, (alpha error). Although that is certainly possible, we believe that trends seen in these 67 subjects are unlikely to be reversed. For example, doubling our sample size to 42 in group EP and 92 for group EM would yield a harmonic mean of 58 subjects, similar in size to the study by Katz et al1 and large enough to detect the difference in preterm delivery seen in that investigation. To achieve such a difference, 11 of the next 21 subjects (52%) enrolled into group EP would need to deliver before 36 weeks, whereas only 5 of 46 (11%) enrolled into group EM could deliver before 36 weeks. That would be a dra172
matic change from the rates of preterm birth for both groups and, although it could happen, we believe it is unlikely. Other possible explanations for the differences between our findings and those seen by Katz et al lie in the differences in study design. Our trial design does not compare ambulatory monitoring to standard care, as does the Katz study. Rather, we compared the pregnancy outcomes for two groups of subjects who both received the nursing support, education, and symptom identification services provided as part of ambulatory monitoring; they differed only in the manner in which uterine activity was assessed. It is possible therefore that the monitoring service, including all it provides, is associated with an improvement in outcome for women with preterm labor, but that the contraction data itself is less important than the nursing service. In fact, we have drawn exactly that conclusion from the comparison study in 266 women at risk of preterm labor.4 Both groups EP and EM in that similarly designed trial experienced a significant decrease in the rates of both preterm labor and preterm delivery over the course of the study, but did not differ from one another. The sample size of 67 in this study is much too small to draw a similar conclusion with confidence, but the findings are consistent. Our prospective enrollment and random assignment to treatment groups also could account for differences in outcome compared with Katz et al. Their matched controlled group allows for the possibility of bias in patient selection and eliminates any possible effect of patient dropout or noncompliance; our design minimizes bias and introduces the possibility that inclusion of subjects who were noncompliant may have affected the results. Daily contact between the nursing staff and patients in both arms of the study allowed frequent assessment of compliance, with noncompliant women being excluded if protocol guidelines were not followed. In a matched control group design such as Katz et al1 report, the control group cannot "dropout" to be noncompliant. The control groups in each study therefore are inherently different. Lastly, demographic differences may exist between our patients and those of Katz et al1 producing different risks for preterm labor. Our study specifically excluded twins, but 33% of monitored subjects and 15% of controls in Katz et al's study had multifetal gestation. The concept of using electronically monitored uterine activity as an endpoint for the adjustment of oral tocolysis and as an early detector of recurrent preterm labor remains attractive despite the current controversy in the literature. Early detection of increased contraction frequency ought logically to lead to improved outcome through earlier institution of tocolysis. Our data do not themselves repudiate that premise, but do indicate that the lessons learned from the application of intrapartum electronic fetal heart rate monitoring in the detection of fetal distress should not be ignored as further research on ambulatory contraction monitoring is designed and
Downloaded by: University of British Columbia. Copyrighted material.
AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 7, NUMBER 2 April 1990
AMBULATORY MONITORING IN PRETERM LABOR/lams, Johnson, O'Shaughnessy
3.
4.
5. REFERENCES
1. Katz M, Gill PJ, Newman RB: Detection of preterm labor by ambulatory monitoring of uterine activity for the management of oral tocolysis. Am J Obstet Gynecol 154: 1253-1256, 1986 2. Newman RB, Gill PG, Wittreich P, Katz M: Maternal percep-
6.
tion of prelabor uterine activity. Obstet Gynecol 68:765— 769, 1986 Morrison JC, Martin JN, Martin RW, Gookin KS, Wiser WL: Prevention of preterm birth by ambulatory assessment of uterine activity: A randomized study. Am J Obstet Gynecol 156:536-543,1987 lams JD, Johnson FF, O'Shaughnessy RW: A prospective random trial of home uterine activity monitoring in pregnancies at increased risk of preterm labor II. Am J Obstet Gynecol 159:595-603, 1988 Porto M, Nageotte MP, Hill O, Keegan KA, Freeman RK: The role of home uterine activity monitoring in the prevention of preterm birth. Abstract 96, presented at the Seventh Annual Meeting of the Society of Perinatal Obstetricians. Lake Buena Vista, Florida, February 6, 1987 Keegan KA, Waffarn F, Quilligan EJ: Obstetric characteristics and fetal heart rate patterns of infants who convulse during the newborn period. Am J Obstet Gynecol 153: 732-737, 1985
Downloaded by: University of British Columbia. Copyrighted material.
executed. As with intrapartum monitoring, it is tempting to believe that more data will automatically produce better outcomes. It is proving to be difficult in both instances to demonstrate that we can use the additional information provided by frequent monitoring to reduce perinatal mortality and morbidity.6
173
AMBULATORY UTERINE ACTIVITY MONITORING IN THE POST-HOSPITAL CARE OF PATIENTS WITH PRETERM LABOR Jay D. lams, M.D., Francee E Johnson, R.N., B.S.N., and Richard W. O'Shaughnessy, M.D.
Care of women with preterm labor has been reported by Katz et al1 to be enhanced by use of an electronic uterine contraction monitor. We enrolled 76 women with singleton gestations who had been successfully treated for preterm labor into a prospective randomized trial, assigning subjects in a ratio of 1:2 to a group of 27 receiving education and self-palpation (EP) or to a group of 49 receiving education and an ambulatory monitor (EM). Subjects in both groups received an intensive education session at entry and were contacted frequently (5 days/week in EP and daily in EM) thereafter to report symptoms and frequency of contractions. Physicians were advised to adjust the dosage of oral tocolytic to maintain fewer than four contractions per hour. Rates of recurrent preterm labor and preterm delivery did not differ between the groups. Although the sample size in this study is too small to exclude entirely the possibility of alpha error, our inability to demonstrate a difference suggests that the improvement reported by others in pregnancy outcome associated with use of an electronic ambulatory contraction monitor may be the result of daily attention to symptoms and signs of preterm labor.
Ambulatory uterine activity monitoring has been reported to be a useful adjunct in the care of women who have had preterm labor.J Daily monitoring of the patient's uterine activity may allow the physician to recognize recurrent preterm labor and to determine the most effective dosage or oral tocolytics. Newman et al2 have found that maternal selfpalpation for uterine activity is not reliable when compared with instrumental tocodynamometry, suggesting that outpatient ambulatory tocodynamometry might represent a significant advance in the care of women who have had preterm labor. Katz and colleagues1 acknowledged that "factors such as daily telephone contact, the availability of an open emergency line, and the post-transmission feedback may all have influenced perinatal outcome" in their study. They recommended that additional studies be performed in other patient populations. We therefore designed a prospective randomized trial of ambulatory tocodynamometry compared with self-palpa-
tion of uterine activity in a population of women treated for preterm labor. MATERIAL AND METHODS
We enrolled 76 women with singleton gestations who had been treated successfully for preterm labor with parenteral tocolysis in a study approved by our Human Subjects Review Committee. Informed consent was obtained, and subjects were assigned randomly in a ratio of 1:2 to the self-palpation group, designated EP (education and palpation), and the monitor group, designated group EM (education plus monitor), respectively. A ratio of 1:2 was chosen to allow us to gain as much experience with the monitor as possible. Six of 27 subjects (22%) assigned to group EP were subsequently excluded for failure to adhere to protocol guidelines; three of 49 women assigned to group EM (6%) were similarly
The Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio Supported by the Tokos Medical Corporation and The March of Dimes
170
Copyright © 1990 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
Downloaded by: University of British Columbia. Copyrighted material.
ABSTRACT
AMBULATORY MONITORING IN PRETERM LABOR/lams, Johnson, O'Shaughnessy
to modify therapy and activity level in both groups based on symptoms, palpated or monitored contraction data, and cervical status. They were advised to adjust the dosage of oral tocolytic medication to maintain a contraction frequency of less than four per hour and to continue oral tocolysis through 36 weeks. Recurrent preterm labor was diagnosed for purposes of the study when women were readmitted to the hospital for parenteral tocolytic therapy. Because of the multiple physicians and hospitals involved, we did not have access to the cervical examination findings for all patients, and therefore thought that parenteral tocolysis was the most comparable endpoint. The frequent contact with subjects in both groups allowed the nursing staff to assess compliance by both patient and physician with protocol guidelines and with Tokos Medical Corporation advisories regarding appropriate use of the Term Guard system. All births before 37 completed weeks of gestation were reviewed in detail by the principal investigator with the project nursing staff and the attending physician to determine the etiology of the preterm delivery. Births before 36 completed weeks were defined as preterm.
Downloaded by: University of British Columbia. Copyrighted material.
excluded. This difference is statistically significant (p < 0.05). All subjects in both groups had recently received parenteral tocolysis with intravenous ritodrine, intravenous magnesium sulfate, or subcutaneous terbutaline, and all were discharged from the hospital on oral betamimetic medication. Subjects were recruited from the private, transport, and clinic populations served by The Ohio State University tertiary perinatal center. All subjects in both groups received an intensive 60- to 75-minute initial educational session about the signs and symptoms of preterm labor from the nursing staff at the Columbus Tokos Perinatal Nursing Center. This was accomplished by telephone or, when possible, in person at the time of hospital discharge. Group EP subjects performed self-palpation of uterine activity for 1 hour twice daily and were contacted by the nursing staff to report symptoms and contraction frequency daily on weekdays and, as needed, on weekends. Group EM subjects used the Term Guard (Tokos Medical Corporation, Santa Ana, California) ambulatory uterine activity monitor to record contractions for 1 hour twice daily and were contacted daily by center staff to report symptoms and transmit monitored contraction data. Subjects in both groups were instructed to call the monitoring center if symptoms were noted and were asked to palpate or record uterine activity whenever they noted symptoms or an increase in perceived contraction frequency. Subjects in both groups who noted symptoms or more than four contractions per hour were instructed to contact their physician; in many instances, the nursing staff also contacted the physician directly to report findings. Physicians were free
RESULTS
The course and outcome of pregnancy for each study subject is shown in Figure 1. The overall rate of preterm delivery before 36 weeks was 14.3% (3 of 21) in group EP and 19.6% (9 of 46) in group EM. Among subjects with recurrent preterm labor, 28.6%
OUTCOME OF PREGNANCY EDUCATION a PALPATION
No Recurrence of Preterm Labor 14 ( 6 7 % )
Recurrent Preterm Labor 7 (33 %)
0
EDUCATION S MONITOR
Indicated Preterm Births 0
0
PROM 1 (4.8 %)
2
PTL—»PTD 2 (9.5%)
5
Term Births 18 (86%)
XGA = 36.9 ±1 8 weeks X BW = 2963 ± 4 1 8 gm
No Recurrence of Preterm Labor 29 (73 %)
Recurrent Preterm Labor 17 ( 3 7 % )
0
0
Indicated Preterm Births 0
0
1
1
PROM 4 (8.7 %)
3
5
PTL—»PTD 5 (10.9%)
11
Term Births
13
26
37 (80 %) X GA= 36.9 ± 2 . 8 weeks XBW= 2845 ± 6 3 0 gm
Figure 1. Course and outcome of pregnancy for subjects in group EP and group EM. PROM: prematurely ruptured membranes; PTL: preterm labor; PTD: preterm delivery; Term: 36 completed weeks of gestation; x GA: mean gestational age in weeks; x BW: mean birthweight in grams.
171
(2 of 7) in group EP, and 35.3% (6 of 17) in group EM delivered before 36 weeks. In group EP, the mean birthweight was 2963 ± 418 gm, and the mean gestational age was 36.9 ± 1.8 weeks. In group EM, average birthweight was 2845 ± 630 gm, and the mean gestational age was 36.9 ± 2.8 weeks. These differences are not significant. Oral tocolysis was continued in 19 of 21 group EP subjects until delivery, spontaneous amniorrhexis, or 36 completed weeks of gestation. One group EP subject discontinued oral tocolysis at 34 weeks because of side effects. In another EP subject, oral tocolytics were stopped at 35!/2 weeks at the patient's request. Both patients delivered at 38 weeks. In group EM, 44 of 46 subjects continued oral tocolysis until delivery, spontaneous rupture of membranes, or 36 weeks' gestation. In group EM, oral tocolysis was discontinued at 35 weeks in two subjects at the patient's request. One woman delivered the next day, and the other at 37 weeks. As mentioned previously, there were significantly (p < 0.05) more dropouts or exclusions in group EP subjects (6 of 27, 22%) than in group EM subjects (3 of 49, 6%). The resulting comparison of 21 subjects in group EP to 46 in group EM yields a harmonic mean of 29. This sample size is sufficient to have demonstrated a decrease in the preterm birth rate at 36 weeks from 45% to 15%, as reported by Morrison et al3 in subjects at risk of preterm labor. It is not large enough to exclude a fall in preterm delivery from 33% to 15% as reported by Katz et al1 in subjects with preterm labor in the current pregnancy, assuming a power of 0.8 and an alpha of 0.05. We would have liked to enroll more patients to achieve greater statistical power, but thought it best to discontinue this trial simultaneously with a concurrently run companion trial enrolling subjects at risk who had not had preterm labor.4 When that trial was closed after reaching the desired sample size, referring physicians became confused over which subjects were eligible for entry and which were not. The resulting uncertainty led to our decision to stop this trial at the same time. DISCUSSION
There are several possible conclusions that might be drawn from the data presented. The first is simply that our sample size is insufficient to demonstrate a difference, (alpha error). Although that is certainly possible, we believe that trends seen in these 67 subjects are unlikely to be reversed. For example, doubling our sample size to 42 in group EP and 92 for group EM would yield a harmonic mean of 58 subjects, similar in size to the study by Katz et al1 and large enough to detect the difference in preterm delivery seen in that investigation. To achieve such a difference, 11 of the next 21 subjects (52%) enrolled into group EP would need to deliver before 36 weeks, whereas only 5 of 46 (11%) enrolled into group EM could deliver before 36 weeks. That would be a dra172
matic change from the rates of preterm birth for both groups and, although it could happen, we believe it is unlikely. Other possible explanations for the differences between our findings and those seen by Katz et al lie in the differences in study design. Our trial design does not compare ambulatory monitoring to standard care, as does the Katz study. Rather, we compared the pregnancy outcomes for two groups of subjects who both received the nursing support, education, and symptom identification services provided as part of ambulatory monitoring; they differed only in the manner in which uterine activity was assessed. It is possible therefore that the monitoring service, including all it provides, is associated with an improvement in outcome for women with preterm labor, but that the contraction data itself is less important than the nursing service. In fact, we have drawn exactly that conclusion from the comparison study in 266 women at risk of preterm labor.4 Both groups EP and EM in that similarly designed trial experienced a significant decrease in the rates of both preterm labor and preterm delivery over the course of the study, but did not differ from one another. The sample size of 67 in this study is much too small to draw a similar conclusion with confidence, but the findings are consistent. Our prospective enrollment and random assignment to treatment groups also could account for differences in outcome compared with Katz et al. Their matched controlled group allows for the possibility of bias in patient selection and eliminates any possible effect of patient dropout or noncompliance; our design minimizes bias and introduces the possibility that inclusion of subjects who were noncompliant may have affected the results. Daily contact between the nursing staff and patients in both arms of the study allowed frequent assessment of compliance, with noncompliant women being excluded if protocol guidelines were not followed. In a matched control group design such as Katz et al1 report, the control group cannot "dropout" to be noncompliant. The control groups in each study therefore are inherently different. Lastly, demographic differences may exist between our patients and those of Katz et al1 producing different risks for preterm labor. Our study specifically excluded twins, but 33% of monitored subjects and 15% of controls in Katz et al's study had multifetal gestation. The concept of using electronically monitored uterine activity as an endpoint for the adjustment of oral tocolysis and as an early detector of recurrent preterm labor remains attractive despite the current controversy in the literature. Early detection of increased contraction frequency ought logically to lead to improved outcome through earlier institution of tocolysis. Our data do not themselves repudiate that premise, but do indicate that the lessons learned from the application of intrapartum electronic fetal heart rate monitoring in the detection of fetal distress should not be ignored as further research on ambulatory contraction monitoring is designed and
Downloaded by: University of British Columbia. Copyrighted material.
AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 7, NUMBER 2 April 1990
AMBULATORY MONITORING IN PRETERM LABOR/lams, Johnson, O'Shaughnessy
3.
4.
5. REFERENCES
1. Katz M, Gill PJ, Newman RB: Detection of preterm labor by ambulatory monitoring of uterine activity for the management of oral tocolysis. Am J Obstet Gynecol 154: 1253-1256, 1986 2. Newman RB, Gill PG, Wittreich P, Katz M: Maternal percep-
6.
tion of prelabor uterine activity. Obstet Gynecol 68:765— 769, 1986 Morrison JC, Martin JN, Martin RW, Gookin KS, Wiser WL: Prevention of preterm birth by ambulatory assessment of uterine activity: A randomized study. Am J Obstet Gynecol 156:536-543,1987 lams JD, Johnson FF, O'Shaughnessy RW: A prospective random trial of home uterine activity monitoring in pregnancies at increased risk of preterm labor II. Am J Obstet Gynecol 159:595-603, 1988 Porto M, Nageotte MP, Hill O, Keegan KA, Freeman RK: The role of home uterine activity monitoring in the prevention of preterm birth. Abstract 96, presented at the Seventh Annual Meeting of the Society of Perinatal Obstetricians. Lake Buena Vista, Florida, February 6, 1987 Keegan KA, Waffarn F, Quilligan EJ: Obstetric characteristics and fetal heart rate patterns of infants who convulse during the newborn period. Am J Obstet Gynecol 153: 732-737, 1985
Downloaded by: University of British Columbia. Copyrighted material.
executed. As with intrapartum monitoring, it is tempting to believe that more data will automatically produce better outcomes. It is proving to be difficult in both instances to demonstrate that we can use the additional information provided by frequent monitoring to reduce perinatal mortality and morbidity.6
173
