London, Dec 7 (IANS): Continuous usage of caesarean sections or c-section may be impacting human evolution as more mothers now need surgery to deliver a baby due to their narrow pelvis size, scientists say.

C-section is the delivery of a baby through a surgical incision in the mother's abdomen and uterus.

"Women with a very narrow pelvis pass on their genes encoding for a narrow pelvis to their daughters," Philipp Mitteroecker from the University of Vienna in Austria, was quoted as saying to bbc.com.

Historically, these genes would not have been passed from mother to child as both would have died in labour.

However, today the global rate of cases where the baby could not fit through the maternal birth canal have increased from 30 in 1,000 in the 1960s to 36 in 1,000 births.

That is about a 10-20 per cent increase of the original rate, due to the evolutionary effect.

Although, the trend is likely to continue, but not to the extent that non-surgical births will become obsolete, the researchers noted.

The research was published in the journal Proceedings of the National Academy of Sciences (PNAS).