Are Caesarian Births Changing Human Evolution?

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New research being conducted at the University of Vienna has shown that regular use of Caesarian sections is affecting human evolution by narrowing the size of the birth canal.

Mothers with Narrow Birth Canals Pass on Their Genes

Cases where a mother’s birth canal is too narrow for the baby to fit down have increased globally from 30 in 1,000 in the 1960’s to 36 in 1,000 in 2016, new research is showing. As a result more mothers are now requiring a C-section to give birth.

Dr Phillip Mitt eroecker, University of Vienna, 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.”

C-sections in the U.S.: the Risks

In the U.S. 1.3 million babies are born each year via C-section. However, almost half of those C-sections might be unnecessary, with the mothers being capable of giving birth normally.

Surgical births that aren’t strictly necessary can put both the mother and the baby at risk. Some of the most common risks are infection of the wound, infection of the womb lining and excessive bleeding.

The Department of Health and Human Services sets a target C-section rate for low-risk births at 23.9 percent. This means that no more than 23.9 percent of low-risk births (pregnant women expecting one child) should be delivered by C-section.

States frequently exceed this target, however, which potentially puts mothers at risk. Florida, Kentucky and Mississippi are the states with the highest numbers of unnecessary C-sections, according to Consumer Reports.

Will this Trend of Evolutionary Change Continue in the Future?

According to the research this trend for narrower birth canals is likely to increase as more and more women get C-sections.

Dr Phillip Mitteroecker said:

“I expect that this evolutionary trend will continue but perhaps only slightly and slowly.”

The researchers said that they did not expect birth by C-section to become the most common method of birth in the future.

Do you think that increasing numbers of C-sections are having a negative impact on our development?