There is no question that C-section rates have been on the rise for many years—they account for about one third of US births— but one of the reasons for this uptick may surprise you. An Austrian study published in the Proceedings of the National Academy of Sciences has found that Caesarean sections seem to be affecting evolution by making birth possible even when a child’s head is too large, a mother’s pelvis is too small, or both.
The findings are based on a mathematical model that used data from the World Health Organization and several other birth studies. The model showed that the problem of babies not fitting in the birth canal, or fetopelvic disproportion, was two-fold. Babies are getting larger, which in most cases is actually healthier, but it does mean that they can have trouble fitting in the birth canal. On the other hand, before C-sections existed, a woman with a very narrow pelvis would not have survived childbirth and therefore been unable to pass the narrow pelvis gene on.
According to the study, “We predict that the regular use of Caesarean sections throughout the last decades has led to an evolutionary increase of fetopelvic disproportion rates by 10 to 20 percent.”
But what's the alternative? Losing women and children in childbirth?
While C-sections may be getting in the way of natural selection, they are undoubtably saving lives.
Lead study author Dr Philipp Mitteroecker is quick to pacify any alarmists. He tells BBC News, "This evolutionary trend will continue but perhaps only slightly and slowly. There are limits to that. So I don't expect that one day the majority of children will have to be born by [Caesarean] sections."
While C-sections may be getting in the way of natural selection, they are undoubtably saving lives. I am a strong proponent of helping people understand the rising C-section rates, especially if it means we can help some women avoid them. However, mothers who have undergone this lifesaving procedure shouldn’t suffer from guilt and shame, and frankly don’t need medical findings that imply they have messed with nature.
If anything, this research should be used to help understand how important and unavoidable many C-sections are. Hopefully, we're emotionally evolved enough to realize that you shouldn't have to die in childbirth just because you have narrow hips or grew a particularly large baby. Our bodies may not have evolved to provide enough room for our larger babies, but our minds have evolved to develop the ability to perform surgery that makes it not just possible, but safe to deliver them.