Breastfeeding

Breast milk is pretty amazing; it has all of the nutrients that a baby needs in the first six months of life. The benefits for the baby are impressive - they include lower rates of allergies, ear and lung infections, obesity, and sudden infant death, as well as healthier weight gain, and other long-term outcomes. That’s compared to infants given cow-milk formula. Moms can benefit from breastfeeding, too. It reduces uterine bleeding, burns calories, and decreases the risk of breast, ovarian, and uterine cancer, as well as osteoporosis, arthritis, type II diabetes, and heart disease. Finally, breastfeeding is free and offers mothers and babies a valuable opportunity to bond from the very first skin-to-skin contact—which should start minutes after birth.

To understand breastfeeding, let’s start with the breasts themselves. Breast tissue develops during puberty, and is made up of adipose or fat tissue, as well as glandular tissue that makes the milk, and lactiferous ducts which serve as passageways which guide the milk to the nipple.

Zooming in on the glandular tissue, there is the alveolus, which is a modified sweat gland made up of alveolar cells which actually make the breast milk. Wrapping around the alveolus are special myoepithelial cells that squeeze down and push the milk out of the alveolus, down the lactiferous ducts, and out one of the pores on the nipple, at which point it enters the baby’s mouth. When the breasts are full of milk they can get heavy, and there are suspensory ligaments called Cooper’s ligaments which help to hold them up against the chest wall.

During pregnancy the placenta releases human placental lactogen and progesterone, and the anterior pituitary gland releases prolactin, and all three of these hormones stimulate the growth of more glandular tissue and prepare the alveolar cells to produce milk. However, even though the breasts are capable of making milk by mid-pregnancy, the high levels of progesterone associated with pregnancy prevent milk letdown. So during pregnancy, the breasts don’t release milk, except for some occasional leakages from the nipples. Overall, the breasts enlarge, the area around the nipple, called the areola, begins to darken, and the areolar glands, also called Montgomery glands, which look like bumps on the areola, start to produce lipoid fluid which moisturizes the nipple.