The first stage of milk that develops during pregnancy is called colostrum. Thick and yellow in color, colostrum lasts a few days after the baby is born. This milk is rich in protein, antibodies, vitamins and minerals.
Approximately two to four days after the baby is born, transitional milk replaces colostrum. Transitional milk is thin and white, and contains high quantities of fat, calories, protein, lactose and vitamins. Many mothers notice the quantity and consistency of their milk changing about two to three days after their baby’s birth.
Approximately 10 to 15 days following baby’s birth, the production of mature milk begins. Mature milk primarily consists of water, and it often appears bluish in color at the beginning of the feeding (foremilk), and turns white toward the end of the feeding (hindmilk) as the milk’s fat content increases. The consumption of hindmilk is essential to ensure the baby is getting adequate nutrition.
A newborn’s stomach is approximately the size of a marble, and the baby’s stomach walls cannot stretch. The amount of colostum produced by a mother’s breasts equals the amount the baby’s stomach can hold. The baby’s stomach increases to roughly the size of a golf ball from seven to 10 days.