Caesareans are making us evolve to have bigger babies, scientists believe.

Caesareans are brilliant. They save lives. But could they also be changing the course of human evolution? Austrian researchers think they’ve found proof that they are.

Throughout history, there have always been women whose birth canal is too narrow to fit their baby’s head. In the past, those women and their babies would have most often died in labour. Thankfully, they can now be saved by c-sections.

But what it means that women with a narrow pelvis are surviving and passing their genes onto their daughters. That means there are more women out there with narrow pelvises, meaning more women needing caesareans.

Dr Philipp Mitteroecker, from the department of theoretical biology at the University of Vienna, says back in the 1960s, three per cent of women had to have caesareans because their babies’ heads were too big to fit through their birth canals. Today, that figure has risen by between 10 and 20 per cent, to an estimated 3.3 to 3.6 per cent of women.


There are plenty of reasons why caesareans are becoming more common. Is evolution one? Photo via iStock.

"Our intent is not to criticise medical intervention," Mitteroecker says. "But it's had an evolutionary effect.

"The pressing question is, what's going to happen in the future? I expect that this evolutionary trend will continue, but perhaps only slightly and slowly."

Listen: this woman wants to take the fear out of labour. 

Mitteroecker also predicts that the trend could lead to more difficult non-caesarean births.

Other scientists have been quick to point out that there are plenty of reasons why the caesarean rate is rising. They talk about diabetes and obesity being more common among women of childbearing age, both of which make c-sections more likely.

That's all true. But what Mitteroecker is saying is that when people express concern about the rising rate of caesareans, they need to take evolution into account.

It's just one more reason to be wary of people pushing the idea that "natural" childbirth is always possible. There have always been women who can't give birth vaginally, and in the future, it seems that there will be more. Yay for caesareans!