Colostrum is breast milk within 3 days after delivery, and pregnancy colostrum is a small amount of milk secreted during pregnancy. Most pregnant women may have a small amount of milk coming out during late pregnancy because the hormone levels in the pregnant woman’s body change during pregnancy, and the hormones stimulate the development of the breasts with a small amount of lactation, which is in preparation for breastfeeding in the future. Colostrum is breast milk from the birth of the baby to the third day after delivery, and the amount of colostrum is relatively small, about 15 to 45 milliliters per day. The composition of both is dominated by fat, lactose and protein, with relatively little fat and lactose and relatively more protein, most of which is globulin. There is a clear difference between colostrum, which is milk from a short period of time after delivery, and milk that overflows from the breasts prior to delivery.