Did you have a c-section delivery?
Did you know that this is a major abdominal surgery? You had your abdominal wall cut through to get to that baby. And, keep in mind, you had a pregnancy with a growing baby that put stress and strain on your body, your pelvic floor, your abdominals.
During pregnancy, the baby grows and pushes on your pelvic floor muscles, not to mention your abdominals. While there may be less stress (possibly) on your pelvic floor than if you had delivered vaginally, there is still some stretch and give that happens on the muscles and joints in the hips and pelvic floor throughout pregnancy.
Your body prepared for a