This 3D animation shows a realistic and medically accurate representation of a child breastfeeding. When your baby suckles, it stimulates nerve endings in the nipple that tell your pituitary gland to release two hormones: prolactin and oxytocin. Prolactin causes your alveoli to take nutrients from your blood supply and turn them into breast milk. Oxytocin causes muscle contractions that push the milk out of the alveoli and through the milk ducts. The release of the oxytocin hormone while breastfeeding will also cause uterine contractions, which helps your uterus return to its pre-pregnancy size. Both prolactin and oxytocin help the mother form an emotional bond with her baby.