According To Scientists, Rise In C-sections Is Affecting Human Evolution

C-sections have been popular among delivery methods for decades, and according to a survey, they make up more than 30 percent of all deliveries in the United States, which back in 1970, was around 5 percent. While they are easier and relatively painless for the mother, an intriguing new study shows that it might not be that harmless after all.

A study by Austrian researchers claims that the widespread use of C-sections can be altering the course of human evolution. Usually, C sections are done in cases where the child’s head is too large for the mother’s pelvis. Historically, larger babies for narrow-hipped moms did not survive the stresses of childbirth, thus did their genes did not pass on to further generations.

But with the widespread use of C-sections has helped these children survive, thus adding to the bigger head/smaller pelvis scenario. So while C-sections have only been around for just a couple of decades, already scientists are speculating that the procedure affecting human evolution.

This is because

Human evolution has always favored people big heads and small hips. This is proportion is great for running and thinking, but a little less ideal for childbirth.

Most other primates (and there are exceptions) have a pelvis-infant ratio more favorable for easy childbirth. We’re in the bottom right, the genus Homo.

This phenomenon has been termed “fetopelvic disproportion,” and the researchers believe that it is on the rise, meaning, the number of babies who have difficulty passing through their mom’s pelvis is increasing. The leads to a consequential rise in C-section rates, although the results are just a mathematical theory for now.

Study researcher Philipp Mitteröcker, who is an evolutionary biologist at the University of Vienna told Vox,

“To my knowledge, this has not been shown empirically yet.”

The results were published in the journal Proceedings of the National Academy of Sciences (PNAS).

And yet some OB-GYNs don’t think the prediction is all that far-fetched.

Dr. Mari Charisse Banez Trinidad, working as an obstetrician at the Mayo Clinic commented on the research,

“It seems like a very reasonable theory. Look at obesity rates in our country and worldwide. As our weights are increasing, so are our babies’ weights. It’s not a far-off proposition that if you have bigger babies, they won’t fit as easily through the pelvis. And if you have pelvic disproportion, C-section is the safest way to deliver.”

This would certainly stir the ire of the proponents of “natural” (i.e., drug-free, vaginal) birth, who claim that the notion of women having small hips and their baby’s head being too big is a “myth.” They argue that women have been successfully giving birth to babies vaginally forever, and there is no reason why they can’t continue to do so.

Alessia Pierdomenico / Reuters

Adding to the controversy is the claim by American College of Obstetrics and Gynecologist calling high C-section rate in the US as a major public health concern. To counter it, they offer guidelines for the prevention of a woman’s first C-section, which in their view leads to more tendency towards surgical births in the future. They also avidly criticize hospitals for having policies where a big baby automatically leads to a C-section.

Trinidad emphasized this is a problem, as, during vaginal deliveries, babies’ heads do mold, ― up to a point.

“Even if it’s a bigger head, molding happens so they can fit through the birth canal,” she said. “But for some babies, that molding is not enough to allow them to be delivered vaginally, safely.”

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