Compared to vaginal deliveries, caesarean deliveries are associated with a decreased risk of urinary incontinence and pelvic prolapse, but an increased risk of miscarriage or placenta previa in future pregnancies. Those are just some of the conclusions on a large literature review on the long-term risks and benefits associated with caesarean delivery, by Sarah Stock from the MRC Centre for Reproductive Health at the University of Edinburgh, UK, and colleagues.
Caesarean delivery rates are rising worldwide, especially for caesareans performed without medical indication. The short-term risks and benefits of caesarean delivery have been well described. In the new study, researchers performed a systemic literature review to identify one randomized controlled trial and 79 cohort studies (29,928,274 participants total) that assessed long-term outcomes following caesarean delivery compared with vaginal delivery.
Compared with vaginal deliveries, caesarean deliveries were found to be associated with a decreased risk of urinary incontinence (1,024/7,306 caesarean delivery versus 7,713/51,594 vaginal delivery; OR 0.56 95% CI 0.47 to 0.66) and pelvic prolapse (116/4,898 caesarean delivery versus 2,055/34,310 vaginal delivery; OR 0.29 95% CI 0.17 to 0.51). Children delivered by caesarean sections had an increased risk of asthma for up to 12 years (4,788/124,668 caesarean delivery versus 23,308/763,292 vaginal delivery; OR 1.21 95% CI 1.11 to 1.32) and obesity up to 5 years of age (834/6,645 caesarean delivery versus 5,295/57,468 vaginal delivery; OR 1.59 95% CI 1.33 to 1.90). Pregnancy after caesarean delivery was associated with an increased risk of miscarriage (2,060/19,106 previous caesarean delivery versus 12,663/132,306 previous vaginal delivery; OR 1.17 95% CI 1.03 to 1.32), stillbirth (496/118,192 previous caesarean delivery versus 1,905/585,370 previous vaginal delivery; OR 1.27 95% CI 1.15 to 1.40), placenta previa (5,039/1,025,692 previous caesarean delivery versus 16,679/6,076,000 previous vaginal delivery; OR 1.74 95% CI 1.62 to 1.87), placenta accreta (44/66,241 previous caesarean delivery versus 188/638,867 previous vaginal delivery), and placental abruption (6,047/858,208 previous cesarean delivery versus 23,855/4,808,952 previous vaginal delivery; OR 1.38 95% CI 1.27 to 1.49).
Given that the findings were predominantly based on observational data, causation cannot be inferred and the findings should be interpreted with caution. Furthermore, the authors were not able to analyse the data by planned (elective) or emergency caesarean.
“This information should help inform discussions about mode of delivery, and may facilitate appropriate personalized delivery planning and shared decision making,” the researchers say.
Abstract
Background: Cesarean birth rates continue to rise worldwide with recent (2016) reported rates of 24.5% in Western Europe, 32% in North America, and 41% in South America. The objective of this systematic review is to describe the long-term risks and benefits of cesarean delivery for mother, baby, and subsequent pregnancies. The primary maternal outcome was pelvic floor dysfunction, the primary baby outcome was asthma, and the primary subsequent pregnancy outcome was perinatal death.
Methods and findings: Medline, Embase, Cochrane, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases were systematically searched for published studies in human subjects (last search 25 May 2017), supplemented by manual searches. Included studies were randomized controlled trials (RCTs) and large (more than 1,000 participants) prospective cohort studies with greater than or equal to one-year follow-up comparing outcomes of women delivering by cesarean delivery and by vaginal delivery. Two assessors screened 30,327 abstracts. Studies were graded for risk of bias by two assessors using the Scottish Intercollegiate Guideline Network (SIGN) Methodology Checklist and the Risk of Bias Assessment tool for Non-Randomized Studies. Results were pooled in fixed effects meta-analyses or in random effects models when significant heterogeneity was present (I2 ≥ 40%).
One RCT and 79 cohort studies (all from high income countries) were included, involving 29,928,274 participants. Compared to vaginal delivery, cesarean delivery was associated with decreased risk of urinary incontinence, odds ratio (OR) 0.56 (95% CI 0.47 to 0.66; n = 58,900; 8 studies) and pelvic organ prolapse (OR 0.29, 0.17 to 0.51; n = 39,208; 2 studies). Children delivered by cesarean delivery had increased risk of asthma up to the age of 12 years (OR 1.21, 1.11 to 1.32; n = 887,960; 13 studies) and obesity up to the age of 5 years (OR 1.59, 1.33 to 1.90; n = 64,113; 6 studies). Pregnancy after cesarean delivery was associated with increased risk of miscarriage (OR 1.17, 1.03 to 1.32; n = 151,412; 4 studies) and stillbirth (OR 1.27, 1.15 to 1.40; n = 703,562; 8 studies), but not perinatal mortality (OR 1.11, 0.89 to 1.39; n = 91,429; 2 studies). Pregnancy following cesarean delivery was associated with increased risk of placenta previa (OR 1.74, 1.62 to 1.87; n = 7,101,692; 10 studies), placenta accreta (OR 2.95, 1.32 to 6.60; n = 705,108; 3 studies), and placental abruption (OR 1.38, 1.27 to 1.49; n = 5,667,160; 6 studies).
This is a comprehensive review adhering to a registered protocol, and guidelines for the Meta-analysis of Observational Studies in Epidemiology were followed, but it is based on predominantly observational data, and in some meta-analyses, between-study heterogeneity is high; therefore, causation cannot be inferred and the results should be interpreted with caution.
Conclusions: When compared with vaginal delivery, cesarean delivery is associated with a reduced rate of urinary incontinence and pelvic organ prolapse, but this should be weighed against the association with increased risks for fertility, future pregnancy, and long-term childhood outcomes. This information could be valuable in counselling women on mode of delivery.
Authors
Oonagh E Keag, Jane E Norman, Sarah J Stock
[link url="http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002494"]PLOS Medicine abstract[/link]