Over the past 150 years, the increase in cesarean sections and changes in food may have led smaller pelvis in women, which may make normal delivery difficult.
A study earlier this month in Research Square revealed that the Women’s basin (or pelvis) has become narrower in the last 150 years.
It is not known exactly what is provoking this change, not all ways as it will affect people’s health. But if the pelvis continues to shrink at this rhythm, caesarean sections may become more frequent-which may have a number of side effects.
On the sidelines of this study, data from 1247 Australian women were analyzed, born Between 1900 and 1984and found that the width of pelvis decreased 0.42 millimeters per year.
Likewise, among 3486 polacas women, the width of the Pelvis decreased 0.47 mm per year, between 1880 and 1970.
Finally, among 320 Mexican women width of Pelvis decreased 0.42 mm per year, between 1900 and 1970.
In the same periods of time, in the countercurrent, the average height increased and shoulder width remained stable or increased.
Speaking to the investigation leader, Maciej Hennebergfrom the University of Adelaide, Australia, points out that this discovery shows that the modern medicine is weakening the impact of natural selection on the pelvis Human – and especially in the width of the birth canal.
In the past, if the baby were too large or the birth canal were too narrow, both the mother and the baby would probably die during delivery. However, caesarean sections – in which the baby is surgically removed through the abdomen – mean that This evolutionary pressure is reduced.
As a result, the delivery channels and pelvis can become narrower.
To the same magazine, the expert Philipp Mitteroeckerfrom the University of Vienna, Austria, who was not involved in the study, agrees that caesarean sections are changing the evolutionary pressures that act on the human childbirth channel.
In a 2016, Mitteroecker predicted precisely that this phenomenon could lead to pelvis to narrow.
The Basin History
Hundreds of thousands of years ago that women receive help from childbirth, often from other women. This cultural practice already diminished the selection pressure on the pelvis and the birth canal.
Then the caesarean sections appeared. They had their peak from the 1970s until the 1990s, with the global rate increased from 7% in 1990 to 21% in 2021.
Lia Bettifrom University College London, is, however, skeptic as to the fact that cesarean sections are the main explanation for the recent change in pelvis width.
In an interview with New Scientist, the expert points out, in turn, that humans were much higher in the same period of time, but this is probably due to diet and better health care – not to an evolutionary change in our genes.
“We know that the diet can affect the pelvis”points out Betti, who was not part of the study.
But there may be other influence. Betti argues that our pelvis are sensitive to many environmental factors, such as the temperature.
Other investigators also described a “new obstetric dilemma” Increased obesity rateswhich can make babies bigger.
“But the real answer is probably a Combination of factors“Betti pointed out.
