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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
Caesarean delivery has immediate known benefits and risks for those women who need help in childbirth. This review measures the long-term outcomes for the mothers’ health, the links to a higher risk of childhood illness and the chance of problems with future pregnancies.
The large review of 80 studies from high-income countries used data from nearly 30 million women and compared caesarean section with vaginal delivery. Caesarean delivery was associated with a lower risk of urinary incontinence and pelvic organ prolapse for mothers, but a higher risk of asthma and obesity for the child. Women who had a caesarean delivery had a higher risk of miscarriage, stillbirth and placental problems in future pregnancies than women who had a vaginal delivery.
All but one study was observational, so we cannot be sure whether delivery method causes these outcomes. This is because the two groups may have included different numbers of women with other risk factors that could also be influencing the outcomes. However, the numbers are very large, and the researchers have taken all the steps they could to make the results reliable.
This study may provide useful information to help women make an informed choice, where there is the opportunity to plan the method of delivery.
Why was this study needed?
Caesarean delivery rates are rising worldwide. A caesarean may be offered to women for clinical reasons such as breech presentation of the baby or multiple pregnancies, but caesarean deliveries without medical indication are also increasing.
In 2012-13, around 25 to 30% of births in UK regions were caesarean deliveries. In England, during that period this divides into 14.8% of births by emergency caesareans and 10.7% by elective (planned) caesarean.
Providing high quality, evidence-based information about the benefits and risks of different modes of delivery is important to help pregnant women plan for childbirth. This study adds information about potential long-term outcomes of delivery for the mother, child and future pregnancies, which may be helpful to ensure women are fully informed.
What did this study do?
This systematic review looked for randomised controlled trials and large (over 1,000 participants) prospective cohort studies or other observational data for analysis. To be included, studies had to report outcomes for caesarean and vaginal delivery at full term (37 weeks or later), for at least one year from the delivery date. The periods varied from 12 months to 20 years or more.
The authors assessed all studies for bias and other quality measures, and they excluded studies which did not provide enough information for this assessment.
The study included one trial and 79 cohort studies, with 29,928,274 participants. Fourteen studies were based partly or fully in the UK. Although some individual studies compared outcomes for elective with emergency caesarean delivery, the overall findings of the systematic review were not reported according to indication.
What did it find?
- Women who had a caesarean delivery were less likely to develop urinary incontinence (9%) than those who had a delivery (15%), odds ratio (OR) 0.56 (95% confidence interval [CI] 0.47 to 0.66). This was based on the eight studies that could be analysed in this way. Two studies found evidence of a lower chance of pelvic organ prolapse after caesarean delivery (5.6%) than in vaginal delivery (6%), OR 0.29 (95% CI 0.17 to 0.51).
- Children who had been born by caesarean section had a slightly higher risk of being diagnosed with asthma by age 12 (3.1%) than children who’d had vaginal delivery (3%), OR 1.21 (95% CI 1.11 to 1.32, based on 13 studies), again with a lot of variation between studies. Six studies showed children born by caesarean were more likely to have become obese by the age of five years (12.5%) compared to children who had vaginal births (9%), OR 1.59 (95% CI 1.33 to 1.90), with a lot of variation between studies.
- Subsequent pregnancies following a caesarean had a slightly higher chance of ending in miscarriage compared with pregnancies after vaginal delivery (OR 1.17, 95% CI 1.03 to 1.32, based on four studies with 151,412 participants), with a high degree of variation between studies. Two studies (91,429 participants) found no difference in perinatal mortality according to of delivery in previous pregnancy.
- About 17 women would need to receive a caesarean delivery (instead of a normal delivery) to prevent one case of subsequent urinary incontinence. About 42 women would be needed to prevent one case of pelvic organ prolapse.
- Regarding harms to the baby, very small increases in risks were noted. About 162 babies would need to be born by caesarean section instead of vaginally for one extra case of childhood asthma, 28 for one extra case of obesity, 69 for an extra miscarriage and 1,144 for an extra stillbirth. Because of the observational nature of the evidence these absolute risk measures (numbers needed to treat) are approximate.
What does current guidance say on this issue?
NICE guidelines on caesarean section (published 2011, updated 2012) recommend that healthcare professionals should discuss the risks and benefits of caesarean and vaginal birth with women, taking into account their circumstances, concerns, priorities and plans for future pregnancies.
This guideline is under review, including its recommendations on birth mode planning. It is expected to consider long-term outcomes.
The Royal College of Obstetricians and Gynaecologists guidelines on birth after previous caesarean birth (2015) recommend discussing future reproductive preferences and chance of successful vaginal birth after caesarean with women who have had previous caesarean deliveries.
What are the implications?
Women planning for a vaginal or caesarean birth based on medical advice, usually wish to ask about their immediate situation and risks. Increasingly women wonder about the long-term effects on themselves, their baby and any future pregnancies, too. This study provides a detailed overview of some of the long-term outcomes despite the lower grade of evidence from observational studies. Randomised trials that quantify all the important outcomes in this clinical area are unlikely to be possible. For now, this review may provide useful information to support discussions between healthcare professionals and pregnant women.
Current clinical guidelines are being updated, and this study could be considered during evidence reviews. It would be helpful if future reviews could consider whether the indications for caesarean delivery (elective or emergency) also affect the long-term outcomes for mother and child.
Citation and Funding
Keag OE, Norman JE, Stock SJ. Long-term risks and benefits associated with caesarean delivery for mother, baby, and subsequent pregnancies: systematic review and meta-analysis. PLoS Med. 2018;15(1):e1002494.
This project received no direct funding.
Bibliography
NICE. Caesarean section. CG132. London: National Institute for Health and Care Excellence; 2011, updated 2012.
NHS website. Caesarean section. London: Department of Health and Social Care; last reviewed 2016.
RCOG. Birth after previous caesarean birth. GTG 45. London: Royal College of Obstetricians and Gynaecologists; 2015.
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