The idea that some people have “birthing hips” or “childbearing hips” is one that is pervasive in our culture. There are songs about it, memes about it, and many, many badly written novels describe women’s bodies in terms of their perceived ability to give birth.

The truth is, you can’t tell a darn thing about a person’s ability to give birth just by looking at them, and the vast majority of pelvis shapes will work for birth. Take a look at these two sets of hips:

They look quite different at first glance, but the major difference between them is in the size of the winglike iliac crest. The green shaded areas are the path through the middle of the pelvis, and they are nearly identical! In real life the soft tissue (muscles, connective tissue, fat and skin) also play a role in the differing external appearance of people’s hips.
Bottom line: You cannot tell anything about a person’s ability to birth based on how their body looks from the outside.

I’ve often heard the “rule” that if a woman has a shoe size smaller than 6, she is destined to be unable to push a baby through the pelvis. There has actually been studies on this! Turns out to be 100% false. You cannot predict someone’s ability to give birth based on shoe size.
Bottom line: You can’t tell anything about a person’s ability to birth based on how their body looks on the outside.

And finally, there’s the myth that plus size women need cesareans more often. It’s true they HAVE cesareans more often, but it’s less clear if they really need them or if there’s a bias at play. There’s a good summary of the facts we do know here. There’s no reason to automatically have a cesarean based on weight alone, and choosing a care provider who is patient and plus size friendly can make it possible.
Bottom line: You can’t tell anything about a person’s ability to birth based on how their body looks on the outside.