Being pregnant can cause permanent changes to your feet; your bundle of joy might cause your feet to get longer and your arches to drop and they don’t go back to the way they were before, so one pregnancy is all it takes to permanently change your feet. Some people think it happens because of the hormones released during pregnancy that increase the give in your ligaments to help open up your pelvis, like relaxin which breaks down collagen and softens your cervix for delivery. While you do get looser and there is an increase in relaxin, a study published in the journal Obstetrics and Gynecology found that the amount of relaxin wasn’t correlated to looseness of joints in pregnant people. So an alternate explanation is that your weight is shifted and increased during pregnancy which may change the pressures on your feet, so maybe it’s more about relaxing than relaxin.