Why do breasts enlarge during pregnancy?
This is nature’s way of preparing the mother for breastfeeding. The placenta makes a lot of estrogen, which, in combination with the other hormones from the pituitary (Prolactin) and other glands, cause the ducts in the breasts to grow larger and form more branches. At the same, progesterone, also secreted by the placenta, stimulates the breasts glandular tissues to enlarge. The alveoli (sacs) are lined with milk-producing cells, and the colostrum (first milk), and the subsequent milk, flows into the collecting ducts and out through the nipples. The estrogen and progesterone (secreted by the placenta) actually inhibit milk production. Immediately after delivery and expulsion of the placenta, the suppression-effect of these two hormones are gone, and milk is secreted, as the Prolactin from the Pituitary Gland stimulates milk production. Indeed, the complex (and yet simple) physiology of the human body is mind-boggling. With all the artificial organs being invented, nothing, even todate,
