It’s jarring for your pelvic organs- organs that have undergone a tremendous amount of anatomical shift during pregnancy and again in the postpartum period. Usually, there are ligaments that firmly tether your organs to their anchor spots inside your body. Under the influence of pregnancy hormones, these ligaments become lax so that your uterus can grow and everything else can get out of the way. Pregnancy hormones take months to be flushed from your body postpartum; and, breastfeeding hormones keep ligaments lax until you’re done weaning. This means that for as long as you’re nursing your baby, your organs are more susceptible to further shift. The direction of organ shift that will occur in response to running is downwards. Read: pelvic organ prolapse.