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.