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How Milk Is Made

How is breast milk made?

Many mothers find they can appreciate their babies' breastfeeding patterns or the need for frequent feedings when they understand how breast milk is produced. Initially, hormones play a greater role. After the first one or two weeks postpartum (after the baby is born), milk removal has a greater effect on the amount of milk produced.

With the expulsion of the placenta after a baby's birth, a drop in the hormones that maintained the pregnancy soon occurs and allows the hormone prolactin to begin to work. Prolactin "tells" the breasts it is time to begin producing large amounts of milk. A mother feels the result of prolactin when her milk "comes in" at around three to five days postpartum. Increased milk production usually occurs at this time even if a baby has not been breastfeeding well or often. However, frequent breastfeeding sometimes speeds up the process of establishing increased milk production. Occasionally, a mother experiences a delay in the production of large amounts of milk.

During the first three to five days, your breasts make colostrum. This is a thick, rich food that is small in volume. It is important to remember that your baby's stomach is very small and does not need large volumes of milk to be filled. If your baby seems satisfied and is making the correct number of wet or dirty diapers, you can feel confident that your body is making everything that your baby needs. Keep nursing when your baby is telling you that he or she is hungry, and your body will respond to the signals to make more milk. 

How much milk is needed?

Ongoing, long-term milk production depends mostly on milk removal. The more often milk is removed and the more completely it is removed, the more milk the breasts make. The opposite is also true. When milk is removed less often or an insufficient amount is removed, the breasts get the signal to slow milk production and make less. Milk removal occurs when a baby effectively breastfeeds.

Effective breastfeeding requires effective sucking by the baby so that enough milk is transferred from the breast into the baby's mouth where it is swallowed. To suck effectively, a baby must latch deeply onto the breast and use the structures in his or her mouth to create intermittent suction, compress the breast with his or her mouth, and swallow. When your baby does this, your body will respond to the signal by releasing the hormone oxytocin. This leads to the release of larger volumes of milk—a process known as milk "let down."  

If a baby is not breastfeeding effectively, milk transfer also can be accomplished through milk expression techniques. Milk can be expressed manually by compressing the breast tissue with your hands. Milk can also be expressed with a breast pump.