NHS Evidence Health Information Resources formerly National Library for Health

Caesarean sections increase the risk of poor outcomes for mothers and babies, reported three national newspapers (31 Oct 2007). These articles were based on a large cohort study the conclusions of which appear appropriate.

The newspaper articles (1-3) reported an increase in the risk of death or serious complications for both mothers and babies after caesarean section. All also reported that caesarean delivery reduced the risk for babies presenting breech (feet or bottom first).
The reports were based on a study published in the BMJ(4). The WHO funded study collected data on 93,000 births from 120 hospitals in 8 Latin American countries. The data showed an approximate doubling in the risk of maternal death or serious complication with planned caesarean section after other explanatory factors had been accounted for. The risk of death for babies presenting breech, delivered by a planned caesarean was one quarter of that following vaginal delivery. The risk of being admitted to intensive care for babies presenting head-first after planned caesarean was doubled.
The newspaper reports each reflected different aspects of the results, but all were essentially correct. The research appears to have been well conducted and the author's conclusions appropriate.

Evaluation of the evidence base for mother and baby outcomes following caesarean delivery

Where does the evidence come from?

The study was co-ordinated by José Villar, a senior lecturer at the University of Oxford and international collaborators. It was funded by the World Health Organisation.

What were the authors' objectives?

The authors intended to evaluate the benefits and harms to mothers and newborns from different types of delivery.

What was the nature of the evidence?

The evidence is from a cohort study of around 97,000 births in 120 health care facilities in eight Latin American countries. It was undertaken over three months, with 91% of all births being included in the analysis.

What were the factors of interest?

The study collected data on maternal deaths and other serious complications: hysterectomy, admission to intensive care, prolonged hospital stay (over seven days) and need for blood transfusion. It also collected data on neonatal deaths or need for intensive care. Additionally, further maternal outcomes (such as vaginal complications, and courses of antibiotics) were evaluated. These outcomes were compared according to the type of delivery - normal (vaginal), caesarean section where the decision was made during labour (urgent caesarean) and planned caesarean section. Other factors that may have confounded the results were examined, including if the baby was a breech (feet first) or cephalic (head-first) presentation.

What were the findings?

Maternal death and serious complications were approximately doubled if the delivery had been a planned caesarean section. A total of 1.8% of mothers having a vaginal birth had a serious complication, with a mortality rate of 0.01%, compared with the planned caesarean group where 5.5% experienced complications and the death rate was 0.04%. The rate of significant vaginal complications was reduced by caesarean section by nine-tenths, from 0.8% to about 0.1%.

For babies who were breech, caesarean deliveries reduced the risk of poor outcomes by three-quarters. Vaginal breech deliveries resulted in the baby dying during delivery in about 9% births, compared with approximately 1% of caesarean deliveries.

Babies who were a cephalic presentation and were born after planned caesarean section were about twice as likely to need intensive care (about 5% compared with 2% of vaginal births).

What were the authors' conclusions?

The authors concluded

caesarean delivery increased maternal death and serious complications when the baby presented head first
delivery by caesarean section is recommended for all breech babies
vaginal complications and fetal death during delivery might be reduced by caesarean section

How reliable are the conclusions?

The authors' conclusions appear to follow from the results of the study. There is a risk with this type of study design that women who planned to have a caesarean had a higher risk of poor outcomes anyway. However, the conclusions are based on a large number of births in a very wide range of practice settings in Latin America, and take account of many other factors that might be alternative explanations for the differences shown. This increases confidence in the findings.

Systematic reviews

Information staff at CRD searched for systematic reviews relevant to this topic. Systematic reviews are valuable sources of evidence as they locate, appraise and synthesize all available evidence on a particular topic.

There were three related systematic review identified on the Cochrane Database of Systematic Reviews (CDSR) (5-7) and one on the Database of Abstracts of Reviews of Effects (DARE) (8).

References and resources

1. Caesarean births twice as risky as natural deliveries. The Independent, 31 October 2007, p9.

2. Death risk higher for women 'too posh to push'. The Daily Telegraph, 31 October 2007, p4.

3. Caesareans 'riskier for mother and baby' according to study of 94,000 women. Daily Mail, 31 October 2007, p12.

4. Villar J, Carroli G, Zavaleta N, Donner A, Wojdyla D, Faundes A, et al. Maternal and neonatal individual risks and benefits associated with caesarean delivery: multicentre prospective study. BMJ Published online 30 October 2007. Doi:10.1136/bmj.39363.706956.55

5. Dodd JM, Crowther CA. Elective repeat caesarean section versus induction of labour for women with a previous caesarean birth. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD004906. DOI: 10.1002/14651858.CD004906.pub2.

6. Dodd JM, Crowther CA, Huertas E, Guise JM, Horey D. Planned elective repeat caesarean section versus planned vaginal birth for women with a previous caesarean birth. Cochrane Database of Systematic Reviews 2004, Issue 4. Art. No.: CD004224. DOI: 10.1002/14651858.CD004224.pub2.

7. Lavender T, Hofmeyr GJ, Neilson JP, Kingdon C, Gyte GML. Caesarean section for non-medical reasons at term. Cochrane Database of Systematic Reviews 2006, Issue 3. Art. No.: CD004660. DOI: 10.1002/14651858.CD004660.pub2.

8.Hicks P. Systematic review of the risk of uterine rupture with the use of amnioinfusion after previous cesarean delivery. Southern Medical Journal 2005;98(4):458-461. [DARE Abstract]