Research has suggested that regular caesarean sections are having an impact on human evolution.
The study claims that more women are having caesarean sections due to their narrow pelvis size, causing the baby to be unable to fit down the birth canal.
Cases such as this were estimated at 36 in 1,000 births in comparison to 30 in 1,000 births in the 1960s.
Authors of the research believe the trend in the caesarean rate is likely to continue, however it is unlikely that non-surgical births will become non-existent.
The abstract from the ‘Cliff-edge model of obstetric selection in humans’ paper says: “The incidence of obstructed labor in humans is strikingly high, in the range of 3 to 6% worldwide. Most of these cases result from the disproportion of the newborn’s head or shoulders and the mother’s pelvic dimensions.
Authors have now raised a discussion as to why the human pelvis has not evolved to be wider over the years.
Dr Philipp Mitteroecker from the Department of Theoretical Biology at The University of Vienna and an author of the research said: “Without modern medical intervention such problems often were lethal and this is, from an evolutionary perspective, selection.
“Women with a very narrow pelvis would not have survived birth 100 years ago. They do now and pass on their genes encoding for a narrow pelvis to their daughters.”
When it came to analysing certain significances found in the research, the paper says: “Because the regular use of caesarean sections has reduced maternal mortality, the model predicts an evolutionary response of fetal or maternal dimensions, increasing the rates of fetopelvic disproportion.”
The ‘Cliff-edge model of obstetric selection in humans’ research paper was published in the Proceedings of the National Academy of Sciences of the United States of America.
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