How Does Your Body Produce Breast Milk?
Breast milk is the perfect baby food. And what’s more? It’s natural and full of life-giving nutrients for your baby. Your body starts preparing to make milk while you’re pregnant itself. You may have noticed tenderness, darkened nipples and swelling in your breasts while you were pregnant. This is all in preparation for the breast milk which will later sustain your baby.

What Happens Inside Your Breasts?
Your developing placenta aids in the release of the hormones progesterone and estrogen which stimulates the very complex biological systems which make milk production possible. Before your pregnancy, your breasts are largely made up of milk glands, protective fat, and supportive tissue. Your breasts have been in preparation for producing breast milk ever since you were a fetus in your own mother’s womb.

The main milk ducts you have now had already formed when you were born. These milk ducts and glands stayed dormant till puberty when a surge of estrogen caused them to swell and grow. When you’re pregnant, the milk glands are at peak performance, shifting to high gear. Your pregnancy hormones then cause the milk ducts which are nestled in layers of fat cells and tissue to grow in size.

Aided by a hormone called prolactin, the clusters of alveoli, which are grapelike sacs found at the end of your milk ducts, take fat, sugars, and protein from your blood to make breast milk. Your milk ducts are fully developed sometime in your second trimester. When your baby is born, your breasts may even be 11/2 pounds heavier.

When you deliver your baby and pass the placenta, the progesterone and estrogen levels in your blood drop drastically, which increases your prolactin levels. This is what ultimately signals your body to make milk.
Breast milk is your baby’s ultimate personalized food. It even changes as your baby grows, in order to meet your baby’s needs at that stage of development. If you’re having trouble breastfeeding, breast pumps are an excellent option to get you used to the motion of feeding.

Article Reviewed By Crystal Ibetoh MD, MBA reviews each article and ensures the accuracy of the health information. Dr. Ibetoh has strong medical interests in women's health and preventative medicine. She is also a mother of three and uses her medical expertise in addition to personal experience to provide advice about breastfeeding.

*The information provided on this site is intended for your general knowledge only and is not a substitute for professional medical advice or treatment. Please consult your healthcare provider with any questions or concerns you may have regarding breastfeeding.*