How Your Breasts Make
And Deliver Milk Within your breasts is a system of milk glands that makes and delivers milk to your baby through your nipples. (1) High up in your breasts are milk glands (the leaves), which are grapelike clusters of cells that make the milk. (2) Milk travels from these glands through your milk ducts (the branches). (3) The milk ducts widen into milk sinuses (the tree trunk), which are underneath your areola, the dark area around your nipples. (4) These sinuses empty into about 20 openings in each of your nipples.
When and how much milk your breasts supply depends on your baby. When your baby first begins to suck, nerves in your nipple send a signal to your pituitary gland to secrete the hormone, prolactin. This hormone helps your glands to produce milk. As your baby keeps sucking, sensors in your nipple send a signal to your pituitary gland to produce another hormone, oxytocin. This hormone makes your milk glands contract to force out through the nipples. This is sometimes called the let-down or ejection reflex. The more your baby sucks, the more milk your breasts make to keep up with the demand.
Your First Milk—Colostrum
The first milk your breasts make is called colostrum. This milk is creamy, yellow, and full of protein and other nutrients. Colostrum also has Vitamin A, Vitamin E, and carotenoids, which help your baby fight infection and diseases. Your breasts make only a small abount of colostrum, so your newborn will have to nurse often to get enough to eat.
Your Second Mature Milk
Gradually over the next week or two, the colostrum will change from yellow to the bluish white color of mature milk. Somewhere between the second and fifth day after birth, you will know when your mature milk “comes in” because it will seem as if your breasts increase in size overnight. Exactly when this happens depends upon how often and how well your baby was able to suck in the first hours and days after birth.
More about Breastfeeding for Beginners
• Overview of Breastfeeding
• When to Feed Your Baby
• How to Feed Your Baby
• Breast Care While Breastfeeding
• Breast and Nipple Problems While Breastfeeding
• Expressing and Storing Breast Milk
• Keeping up the Milk Supply
• Nutrition While Breastfeeding
• Breastfeeding in Special Situations
• Returning to Work While Breastfeeding
• Resources for Support While Breastfeeding
Tips From Baby:
• When I suck, it helps start your milk flowing.
• Breast milk helps me fight disease and grow.