How Your Breasts Produce Milk

How Your Breasts Produce Milk

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Milk is produced in the milk-producing glands in the breasts, called alveoli. Milk collects in pockets, or lactiferous sinuses under the areola (the dark circle surrounding the nipple). Regular and effective breastfeeding or pumping stimulates the production of breastmilk by causing the release of hormones from the mother's pituitary gland. Prolactin and oxytocin are the hormones of breastfeeding.

Prolactin is released starting in the second half of pregnancy and causes the production of milk to begin in the alveoli. Milk is not produced in large quantities during pregnancy as the hormones of pregnancy suppress lactation. When the placenta is expelled at birth, suppression of prolactin and oxytocin ceases and Colostrum flows freely.

Colostrum is the perfect first food for your baby, both in amount and content. Colostrum has a high concentration of immunoglobulins and acts as baby's first "inoculation." Receiving your colostrum helps provide your baby a measure of protection against many illnesses and infections. Regular stimulation of the nipple and areola, along with breastfeeding or pumping to effectively remove breastmilk, sends the message to the mother's brain to product prolactim.

Oxytocin stimulates the small muscles around the alveoli to contract, causing milk to flow from the alveoli into the milk (lactiferous) ducts, and into the milk (lactiferous) sinuses in the breasts. This hormonal response causes milk to become readily available to baby as it enters into these sinuses. The Milk Ejection Reflex or MER (also called "let-down") is the physical response of a mother's body to the hormones of lactation, Many mothers experience MER as a warm or tingling feeling. Others describe it as a "pins and needles" type of feeling, while others feel no sensation at all. The sensation may start high in the chest or under the armpit and may flow downward. Some mothers may experience the MER as a sudden feeling of sleepiness or of thirst. All of these responses are normal.

Babies often begin breastfeeding with a quick, shallow "flutter" suck. Milk begins to drip and flow and, as it does, babies switch to a slower and more rhythmic sucking pattern. A baby who is drinking well latches on with a wide open mouth, draws a large amount of breast tissue and feeds with a rhythmic suck-swallow-breathe pattern, where the baby's lower jaw will open wide, pause, then close. The mother can usually hear the swallowing of milk frequently when baby is drinking well.

When latched well and drinking milk at the breast, baby receives both foremilk and hindmilk. Foremilk contains more sugar and water, enticing the baby to suck. Hindmilk, the higher-fat, higher-calorie milk, increases towards the end of the feeding. To insure that the baby gets the full feed, let the baby decide when to finish with the first breast. Don't watch the clock, but instead, watch your baby. Most of the time, a baby will drink well and then come away from the breast ready to move to the other breast. Some babies may feel full after one side and need to rest for a while before taking the other breast. If you are concerned about how much your baby is getting, call your health care provider or breastfeeding specialist.