Women usually get a rather wide pelvis at the end of 20

Wider pelvis to facilitate the birth
Women naturally have a slightly wider pelvis than men, so there is enough room for the baby's head at birth. As a Swiss study has now shown, the pelvis is apparently particularly wide when the woman reaches her most fertile age. As the scientists of the University of Zurich currently report in the journal "Proceedings of the National Academy of Sciences", the width of the female pelvic girdle increases sharply from the beginning of puberty, but then gets narrower again from about 40 years. This "reprogramming" is therefore probably directly related to the changes in the female hormone balance.

Broadening begins with the onset of puberty
If a woman in the middle of the body is built relatively broad, this colloquially is often referred to as a "happy pelvis". Not without reason, because the female pelvis expands in the course of childbearing time to prepare the body for an impending birth. A wide pelvis facilitates the exit of the child, while a very narrow pelvic outlet can cause complications during childbirth. Now researchers around Marcia Ponce de León of the University of Zurich report in the "Proceedings" how these changes in the female anatomy are going on. Accordingly, the broadening begins from the beginning of puberty until the female pelvic girdle reaches its maximum width at the most fertile time. Later in life, the pelvis will narrow again.

The pelvis of the woman becomes ever wider from puberty. (Image: BillionPhotos.com/fotolia.com)

"From the age of about ten, women's development will change substantially as male development continues its earlier course," the experts write in their article. "Around the age of 40 to 45 years, female development is changing again, in a direction that is broadly in line with male development," the researchers added.

In childhood only slight differences between the sexes
The scientists had examined a total of 275 healthy persons for their project using computed tomography (CT) in order to be able to follow the development of the pelvis over the course of time. It turned out that between the genders there are small differences in this area from the outset - but these became really clear only at the beginning of puberty. For between 15 and 25 years of age, women would change the position of the ischial-pubic region, thereby broadening the pelvic outlet and the distances between the acetabular cups. "All in all, these developmental changes lead to a broad, birth-friendly birth canal," the team added. These changes would culminate between the ages of 25 and 30, with the researchers saying that it does not matter if the woman gave birth to a child or not.

Interplay of genes and hormones
This particular structure of the female pelvis is probably due to a complex interaction of hormones such. Attributed to estrogen and certain genes and would remain until menopause. "The female organism can obviously widen the pelvis on demand and is not simply at the mercy of a genetically determined development program", Ponce de León is quoted in a statement from the University of Zurich. At the same time, hormones are also strongly influenced by diet and environmental factors. "Birth problems are less an evolutionary problem. Rather, it seems to be a matter of balance between the hormones and external factors that affect the size of the birth canal and the prenatal development of the child. "

But why does the width of the pelvis reduce again after the woman's childbearing age? According to the researchers, this is probably related to the upright gait. For a narrower pelvis stabilizes the pelvic floor and thereby helps to absorb the high pressure created by walking in the abdomen. "During a woman's life, the dilemma is first defused in one direction, by widening the birth canal during the most fertile phase, and then in the other by narrowing the postmenopausal dimensions," the researchers conclude in their article. (No)