Rising caesarean section rates: can evolution and ecology explain some of the difficulties of modern childbirth?

There is concern in many countries about rising rates of caesarean section. In England and Wales, for example, the figure is about 22%,1 whereas the World Health Organization favours 10-15%. Most comments on the rising trend, whether from the medical profession or from the public, express disapproval, an example being the report of a Parliamentary Select Committee. In response, obstetricians in the UK have set up studies such as the National Sentinel Audit (England and Wales)1 and the National Audit (Scotland).2 In Canada the matter is being addressed by the Ontario Women's Health Project.3 These bodies note that in primary emergency caesarean section (i.e. caesarean section in primigravid women in labour) there are two main indications—failure to progress in labour and fetal distress. To counter these they advocate generous use of oxytocin in the failure-to-progress group (a strategy that can precipitate fetal distress) and careful evaluation of the fetus via scalp pH in the fetal-distress group. But such exhortations have had scant effect on the caesarean section rate. Further, when a caesarean section has been done for the first baby, there is a tendency to deliver subsequent babies in the same way; thus, an increase in the primary caesarean section rate has a multiplier effect on the whole rate. Why is it that modern human childbirth is so frequently associated with difficulty? Only occasionally has anyone attempted to explain this.4 While the proximate causes for primary caesarean section are failure to progress and fetal distress, the ultimate causes may lie in changes in human ecology.