Declaring that someone has "childbearing hips" is one of those creepy compliments that just doesn't quite sit right — like saying someone looks "fertile" or calling someone a "natural" beauty. Most of the time, when people say "childbearing," they mean to remark on the size of a person's hips. But are some people's hips literally built better for carrying and birthing a baby? Well, in a way.
The reason why some people have wider hips than others really has to do with the size and shape of their pelvis, explains Lakeisha Richardson, MD, FACOG, an Ob/Gyn in Greenville, MS. There are technically four standard pelvis shapes: gynaecoid, android, anthropoid, and platypelloid, she says. The gynaecoid pelvis is the most common shape, and about half of people with vaginas have a gynaecoid pelvis, she says.
In general, a gynaecoid-shaped pelvis tends to facilitate vaginal birth the easiest. Gynaecoid pelvises are very wide and shallow, which provides a nice cradle for the baby, says Daniel Roshan, MD, FACOG, FAC, an Ob/Gyn in New York City. Additionally, "the gynaecoid shape has an oval outlet and a wide arch that makes childbirth easier," Dr. Richardson says. On the other hand, the android pelvis tends to be deep and narrow, which makes it more difficult for a baby to exit, he says. A platypelloid-shaped pelvis is typically narrow and small, so it's very difficult to deliver a baby vaginally, he says. And the anthropoid looks like a cross between the platypelloid and the android, and it's kind of shaped like a heart, which can make it somewhat tougher to deliver.
Now, you can't tell what type of pelvis you have just by looking in the mirror. Usually, when an Ob/Gyn examines a pregnant person at 37-38 weeks, they can check the width and size of a pregnant person's pelvis, to prepare for childbirth, Dr. Roshan says. While the cartilage between the bones tends to relax or loosen up during pregnancy to accommodate for childbirth, the pelvis shape does not change, Dr. Richardson says.
But pelvis structure is just one factor that influences a person's birth experience. Doctors usually have three variables that they keep in mind: power, passage, and passenger, Dr. Roshan says. Power refers to a person's contractions and pushing, passenger is the size of the baby, and passage is the size and shape of the pelvis, he says. For example, if you have a gynaecoid-shaped pelvis and a large baby, you might not be able to push it out. Likewise, if you have a tiny platypelloid-shaped pelvis and a small baby, you might be totally chill.
Ultimately, child birth is difficult no matter what kind of pelvis you've got, and plenty of people deliver babies wonderfully regardless of the size of their body. Also, it's super important to remember that you can't tell anything about a person's health just by looking at them — including how well they'd be able to deliver a baby vaginally.