143
BIRTH 40:2 June 2013
IN THE LITERATURE COMMENTARY ON: Karlstr€ om, A, Lindgren, H, Hildingsson, I. Maternal and infant outcome after caesarean section without recorded medical indication: findings from a Swedish case–control study. BJOG 2013;120(4):479–486.
The University of British Columbia Michael C. Klein, MD, CCFP, FAAP (Neonatal/Perinatal), FCPS, ABFP ABSTRACT: This study is one of a series of recent publications that attempt to sort out the impact of mode of birth on maternal and newborn outcome. The focus on elective cesarean section compared to planned vaginal birth beginning in spontaneous labor is an improved methodology over the earlier comparisons that failed to be able to separate planned from unplanned cesarean section or vaginal birth. The retrospective case control methodology based on birth record data that is employed in this research is similar to others, though with more respectable numbers. Most suffer from the problem of ascertainment difficulties, failure to stratify by parity, and of course, the unavailability of randomization, which some consider the ideal methodology. (BIRTH 40:2 June 2013)
Key words: cesarean section, elective cesarean section, maternal and newborn morbidity, maternal choice, mode of delivery
Evaluation The study by Karlstr€ om et al is one of a series of studies that employ retrospective methodologies to try to sort out the role of the birth mode in outcomes for mother and newborn. This particular study uses 5,877 birth records from the Swedish National Birth Register of women undergoing elective cesarean section in a casecontrol of study, comparing 13,774 women who began labor spontaneously and had none of a large number of Michael C. Klein is Professor Emeritus in the Departments of Family Practice and Pediatrics; Director, Clinical Scholars Program, Department of Family Practice University of British Columbia; and Senior Scientist Emeritus, BC Child and Family Research Institute, Centre Developmental Neurosciences & Child Health, Children’s and Women’s Health Centre of British Columbia, Vancouver, British Columbia, Canada. Address correspondence to Michael C. Klein, Clinical Services Building Room V3-3, 948 West 28th Avenue, Vancouver, BC, Canada V6H 3N1.
© 2013, Copyright the Authors Journal compilation © 2013, Wiley Periodicals, Inc.
high risk conditions. The vaginal comparision group was further divided into those who ended up with an emergency cesarean section. Only elective cesarean sections with singleton vertex position were included. On the vaginal birth side, inductions were excluded. This was different from studies that employed elective breech births as a surrogate for the cesarean comparision.(1,2) Information on actual maternal request electives was unavailable, though there was an assumption that some or many were from among women who made such a request, absent conventional indications. In this study, maternal complications were more common among women undergoing elective cesarean section. These included bleeding complications, OR 2.5 (95% confidence interval [CI] 2.1–3.0), and infections, OR 2.6 in both groups. Breastfeeding complications were more common in the elective cesarean section group, OR 6.8 (CI 3.2–14.5). Newborn respiratory outcomes strongly favored the vaginal route and hypoglycemia was twice as common in the cesarean group. In my view, it is not legitimate to compare primary outcomes for those receiving emergency cesarean section, despite the admittedly less desirable outcomes for this
BIRTH 40:2 June 2013
144 group, as women cannot know to which group they will find themselves. It only makes sense to compare those women who start down the vaginal pathway with those who follow the elective route. Apgar scores were not useful as the authors could not separate by timing of the scoring. While these results based on odds ratios may seem impressive, in absolute terms the differences were relatively small: bleeding complications 9.9 versus 5.0%, infections 2.5 versus 1.0%, breastfeeding complications 1.2 versus 0%, elective cesarean versus planned vaginal birth, respectively. The newborn outcomes follow similar orders of magnitude. The main difficulty is that this study cannot really determine if the elective cesarean sections really represented cesareans on maternal request or just those without indications specified. Yet this type of study continues to be published. The first and most impressive of this type of study was the one in 2007 by Liu et al (1) They used cesarean sections for breech births as the surrogate for elective and compared them to women who began labor vaginally, obviously with the intention of having a vaginal birth. The large numbers from across Canada were its great strength. The planned cesarean group comprised 46,766 women versus 2,292,420 in the planned vaginal delivery group. Overall rates of severe morbidity were 27.3 and 9.0, respectively, per 1000 deliveries. The planned cesarean group had increased postpartum risks of cardiac arrest (adjusted odds ratio 5.1, 95% CI 4.1–6.3), wound hematoma (OR 5.1, 95% CI 4.6–5.5), hysterectomy (OR 3.2, 95% CI 2.2–4.8), major puerperal infection (OR 3.0, 95% CI 2.7–3.4), anesthetic complications (OR 2.3, 95% CI 2.0–2.6), venous thromboembolism (OR 2.2, 95% CI 1.5–3.2) and hemorrhage requiring hysterectomy (OR 2.1, 95% CI 1.2– 3.8), and stayed in hospital longer (adjusted mean difference 1.47 days, 95% CI 1.46–1.49 days) than those in the planned vaginal delivery group, but a lower risk of hemorrhage requiring blood transfusion (OR 0.4, 95% CI 0.2–0.8). While absolute risk increased in the elective group, severe maternal morbidity rates were low (e.g., for postpartum cardiac arrest, the increase with planned cesarean delivery was 1.6 per 1000 deliveries, 95% CI 1.2–2.1). In a similar era to Karlstr€ om, the Bodner study (2) of 178 women undergoing elective cesaran section, compared with the next woman with a similar parity, showed an increase in maternal wound infection, hemorrhage, fever, need for iron supplimentation, breastfeeding problems, longer hospaital stays in the elective cesarean section versus the planned vaginal birth group. The study was powered only for wound infections and therefore the newborn outcomes showing little difference by birth mode could shed little light on actual newborn outcomes—and the study took place in
an environment with a rather strange management style, as judged by a high use of oxytocin augmentation (70.8%) despite a 5.6% epidural rate. Studies that call for a randomized controlled trial as the only way to sort out the methodological confusion are problematic. What kind of a woman would be in equipoise as to her chosen mode of birth? And if such women were to be found, would they not be so unusual that it would be difficult to generalize about the results. And the trial would take so long to conduct that the societal values and medical/surgical approaches would likely have shifted substantially from the beginning to the end of the study. It was based on this kind of rather weak data that the National Institutes of Health (NIH) Consensus Conference on so-called maternal request (3) made the recommendation that if women were planning several births they ought to avoid the first cesarean section, when the data clearly showed even the second cesarean set up a cascade of future placentation problems (4,5). This flawed recommendation in turn has led to a continuation of the recommendation from the American College of Obstetricians and Gynecologists (6) that, while elective cesarean section ought not be performed before 39 weeks of gestation, a woman ought to be discouraged from an elective only if she plans more than several pregnancies. The history of bladder, bowel, sexual and maternal request studies since 1948 and since the NIH conference, and the weaknesses of the methodology upon which current recommendations are being made, has been recently reviewed in this journal (7). An important and often forgotten consideration in the evaluation of the effect of elective cesarean section compared with planned vaginal birth is the reality that, while cesarean section has become a highly standardized procedure repeatedly practiced in specialist training programs, the management of normal vaginal birth is not only neglected in training but subjected to few controls. Moreover, the comparative data about vaginal birth is hospital-based and often attended by house and attending staff with variable skills. A more appropriate comparison group would be vaginal births attended by specialists in the normal—midwives—compared with cesarean sections by obstetrician-gynecologist surgeons.
References 1. Liu S, Liston RM, Joseph KS, et al. Maternal mortality and severe morbidity associated with low-risk planned cesarean delivery versus planned vaginal delivery at term. Can Med Assoc J 2007;176(4):455–460. 2. Bodner K, Wierrani F, Gr€unberger W, et al. Influence of the mode of delivery on maternal and neonatal outcomes: A comparison
BIRTH 40:2 June 2013
between elective cesarean section and planned vaginal delivery in a low-risk obstetric population. Arch Gynecol Obstet 2011; 283(6):1193–1198. 3. National Institutes of Health State-of-the-Science Conference Statement. Cesarean delivery on maternal request March 27–29, 2006. [Editorial]. Obstet Gynecol 2006;107(6):1386–1397. 4. Hemminki E, Merilainen J. Long-term effects of cesarean sections: ectopic pregnancies and placental problems. [see comment]. Am J Obstet Gynecol 1996;174(5):1569–1574.
145 5. Hemminki E, Shelley J, Gissler M. Mode of delivery and problems in subsequent births: A register-based study from Finland. Am J Obstet Gynecol 2005;193(1):169. 6. American College of Obstetricians and Gynecologists. Cesarean delivery on maternal request: Committee opinion no 559. Obstet Gynecol 2013; 121: 904–907. 7. Klein MC. Cesarean section on maternal request: A societal and professional failure and symptom of a much larger problem. Birth 2012;39(4):305–310.
BIRTH 40:2 June 2013
IN THE LITERATURE COMMENTARY ON: Karlstr€ om, A, Lindgren, H, Hildingsson, I. Maternal and infant outcome after caesarean section without recorded medical indication: findings from a Swedish case–control study. BJOG 2013;120(4):479–486.
The University of British Columbia Michael C. Klein, MD, CCFP, FAAP (Neonatal/Perinatal), FCPS, ABFP ABSTRACT: This study is one of a series of recent publications that attempt to sort out the impact of mode of birth on maternal and newborn outcome. The focus on elective cesarean section compared to planned vaginal birth beginning in spontaneous labor is an improved methodology over the earlier comparisons that failed to be able to separate planned from unplanned cesarean section or vaginal birth. The retrospective case control methodology based on birth record data that is employed in this research is similar to others, though with more respectable numbers. Most suffer from the problem of ascertainment difficulties, failure to stratify by parity, and of course, the unavailability of randomization, which some consider the ideal methodology. (BIRTH 40:2 June 2013)
Key words: cesarean section, elective cesarean section, maternal and newborn morbidity, maternal choice, mode of delivery
Evaluation The study by Karlstr€ om et al is one of a series of studies that employ retrospective methodologies to try to sort out the role of the birth mode in outcomes for mother and newborn. This particular study uses 5,877 birth records from the Swedish National Birth Register of women undergoing elective cesarean section in a casecontrol of study, comparing 13,774 women who began labor spontaneously and had none of a large number of Michael C. Klein is Professor Emeritus in the Departments of Family Practice and Pediatrics; Director, Clinical Scholars Program, Department of Family Practice University of British Columbia; and Senior Scientist Emeritus, BC Child and Family Research Institute, Centre Developmental Neurosciences & Child Health, Children’s and Women’s Health Centre of British Columbia, Vancouver, British Columbia, Canada. Address correspondence to Michael C. Klein, Clinical Services Building Room V3-3, 948 West 28th Avenue, Vancouver, BC, Canada V6H 3N1.
© 2013, Copyright the Authors Journal compilation © 2013, Wiley Periodicals, Inc.
high risk conditions. The vaginal comparision group was further divided into those who ended up with an emergency cesarean section. Only elective cesarean sections with singleton vertex position were included. On the vaginal birth side, inductions were excluded. This was different from studies that employed elective breech births as a surrogate for the cesarean comparision.(1,2) Information on actual maternal request electives was unavailable, though there was an assumption that some or many were from among women who made such a request, absent conventional indications. In this study, maternal complications were more common among women undergoing elective cesarean section. These included bleeding complications, OR 2.5 (95% confidence interval [CI] 2.1–3.0), and infections, OR 2.6 in both groups. Breastfeeding complications were more common in the elective cesarean section group, OR 6.8 (CI 3.2–14.5). Newborn respiratory outcomes strongly favored the vaginal route and hypoglycemia was twice as common in the cesarean group. In my view, it is not legitimate to compare primary outcomes for those receiving emergency cesarean section, despite the admittedly less desirable outcomes for this
BIRTH 40:2 June 2013
144 group, as women cannot know to which group they will find themselves. It only makes sense to compare those women who start down the vaginal pathway with those who follow the elective route. Apgar scores were not useful as the authors could not separate by timing of the scoring. While these results based on odds ratios may seem impressive, in absolute terms the differences were relatively small: bleeding complications 9.9 versus 5.0%, infections 2.5 versus 1.0%, breastfeeding complications 1.2 versus 0%, elective cesarean versus planned vaginal birth, respectively. The newborn outcomes follow similar orders of magnitude. The main difficulty is that this study cannot really determine if the elective cesarean sections really represented cesareans on maternal request or just those without indications specified. Yet this type of study continues to be published. The first and most impressive of this type of study was the one in 2007 by Liu et al (1) They used cesarean sections for breech births as the surrogate for elective and compared them to women who began labor vaginally, obviously with the intention of having a vaginal birth. The large numbers from across Canada were its great strength. The planned cesarean group comprised 46,766 women versus 2,292,420 in the planned vaginal delivery group. Overall rates of severe morbidity were 27.3 and 9.0, respectively, per 1000 deliveries. The planned cesarean group had increased postpartum risks of cardiac arrest (adjusted odds ratio 5.1, 95% CI 4.1–6.3), wound hematoma (OR 5.1, 95% CI 4.6–5.5), hysterectomy (OR 3.2, 95% CI 2.2–4.8), major puerperal infection (OR 3.0, 95% CI 2.7–3.4), anesthetic complications (OR 2.3, 95% CI 2.0–2.6), venous thromboembolism (OR 2.2, 95% CI 1.5–3.2) and hemorrhage requiring hysterectomy (OR 2.1, 95% CI 1.2– 3.8), and stayed in hospital longer (adjusted mean difference 1.47 days, 95% CI 1.46–1.49 days) than those in the planned vaginal delivery group, but a lower risk of hemorrhage requiring blood transfusion (OR 0.4, 95% CI 0.2–0.8). While absolute risk increased in the elective group, severe maternal morbidity rates were low (e.g., for postpartum cardiac arrest, the increase with planned cesarean delivery was 1.6 per 1000 deliveries, 95% CI 1.2–2.1). In a similar era to Karlstr€ om, the Bodner study (2) of 178 women undergoing elective cesaran section, compared with the next woman with a similar parity, showed an increase in maternal wound infection, hemorrhage, fever, need for iron supplimentation, breastfeeding problems, longer hospaital stays in the elective cesarean section versus the planned vaginal birth group. The study was powered only for wound infections and therefore the newborn outcomes showing little difference by birth mode could shed little light on actual newborn outcomes—and the study took place in
an environment with a rather strange management style, as judged by a high use of oxytocin augmentation (70.8%) despite a 5.6% epidural rate. Studies that call for a randomized controlled trial as the only way to sort out the methodological confusion are problematic. What kind of a woman would be in equipoise as to her chosen mode of birth? And if such women were to be found, would they not be so unusual that it would be difficult to generalize about the results. And the trial would take so long to conduct that the societal values and medical/surgical approaches would likely have shifted substantially from the beginning to the end of the study. It was based on this kind of rather weak data that the National Institutes of Health (NIH) Consensus Conference on so-called maternal request (3) made the recommendation that if women were planning several births they ought to avoid the first cesarean section, when the data clearly showed even the second cesarean set up a cascade of future placentation problems (4,5). This flawed recommendation in turn has led to a continuation of the recommendation from the American College of Obstetricians and Gynecologists (6) that, while elective cesarean section ought not be performed before 39 weeks of gestation, a woman ought to be discouraged from an elective only if she plans more than several pregnancies. The history of bladder, bowel, sexual and maternal request studies since 1948 and since the NIH conference, and the weaknesses of the methodology upon which current recommendations are being made, has been recently reviewed in this journal (7). An important and often forgotten consideration in the evaluation of the effect of elective cesarean section compared with planned vaginal birth is the reality that, while cesarean section has become a highly standardized procedure repeatedly practiced in specialist training programs, the management of normal vaginal birth is not only neglected in training but subjected to few controls. Moreover, the comparative data about vaginal birth is hospital-based and often attended by house and attending staff with variable skills. A more appropriate comparison group would be vaginal births attended by specialists in the normal—midwives—compared with cesarean sections by obstetrician-gynecologist surgeons.
References 1. Liu S, Liston RM, Joseph KS, et al. Maternal mortality and severe morbidity associated with low-risk planned cesarean delivery versus planned vaginal delivery at term. Can Med Assoc J 2007;176(4):455–460. 2. Bodner K, Wierrani F, Gr€unberger W, et al. Influence of the mode of delivery on maternal and neonatal outcomes: A comparison
BIRTH 40:2 June 2013
between elective cesarean section and planned vaginal delivery in a low-risk obstetric population. Arch Gynecol Obstet 2011; 283(6):1193–1198. 3. National Institutes of Health State-of-the-Science Conference Statement. Cesarean delivery on maternal request March 27–29, 2006. [Editorial]. Obstet Gynecol 2006;107(6):1386–1397. 4. Hemminki E, Merilainen J. Long-term effects of cesarean sections: ectopic pregnancies and placental problems. [see comment]. Am J Obstet Gynecol 1996;174(5):1569–1574.
145 5. Hemminki E, Shelley J, Gissler M. Mode of delivery and problems in subsequent births: A register-based study from Finland. Am J Obstet Gynecol 2005;193(1):169. 6. American College of Obstetricians and Gynecologists. Cesarean delivery on maternal request: Committee opinion no 559. Obstet Gynecol 2013; 121: 904–907. 7. Klein MC. Cesarean section on maternal request: A societal and professional failure and symptom of a much larger problem. Birth 2012;39(4):305–310.
