A few weeks ago my mother told me something that I found strange. After getting her a pair of shoes and guessing on her size, she told me that she used to be a size 5 but now, after having two kids, is a size 6. “Your feet grow during pregnancy,” she said when I looked at her in confusion. “Everyone knows that.”
But does everyone know that? I definitely didn’t know that, and I’m a health editor and a hypochondriac.
It turns out that it’s absolutely true: Many people note a slight increase in shoe size after pregnancy. Researchers think this shift in plantar size is the result of a combination of added pressure on the musculoskeletal system and a surge in a hormone called relaxin (yes, that’s what it’s actually called). During pregnancy, the body’s production of relaxin is as much as 10-times greater than it is normally. The aptly named hormone is secreted by the ovaries and placenta, and its main job is to relax the ligaments in the pelvis and soften and widen the cervix.
But relaxin doesn’t just make ligaments in the pelvic area chill out; it relaxes just about every ligament in the body, including the feet. Combine that with the increased weight of a growing baby and the body it takes to support it, and the end result is a relaxing of the foot’s arch. That elongates the foot, making it bigger. That’s what researchers currently believe to be the cause, anyway. As we discuss on the podcast, there’s still a lot of research to be done on this phenomenon—and it’s probably not at the top of anyone’s list.
By Claire Maldarelli