The rise in Caesarean section births is now affecting human evolution, according to a new study. Researchers at the University of Vienna found that in 36 of 1,000 pregnancies today, the baby is too big to fit down the maternal birth canal. This figure is up from 30 in 1,000 pregnancies in the '60s. Dr Philipp Mitteroecker of the University of Vienna explained this increase by telling the BBC: "Women with a very narrow pelvis would not have survived birth 100 years ago. They do now [because of Caesareans] and pass on their genes encoding for a narrow pelvis to their daughters." According to the NHS, around one in every four to five pregnant women in the UK gives birth by Caesarean. The University of Vienna researchers also found that the rise in C-sections is helping more babies to be born bigger, because cases of fetopelvic disproportion – where the baby doesn't fit through the maternal birth canal – are less likely to prevent a healthy birth. Dr Mitteroecker predicted that though this evolutionary trend is likely to continue, it should do so "only slightly and slowly". "There are limits to that," he told the BBC. "So I don't expect that one day the majority of children will have to be born by [Caesarean] sections." Despite the increase in C-section births, the procedure still carries some unfair negative connotations. One British mum recently shared a picture of her C-section scar on Facebook in a bid to combat this stigma.