Breast swelling is normal in the first few weeks of life. In fact, breast nodules can be felt in most infants, both boys and girls. In fact, some babies even secrete milk, usually within that first week.
Breast development is partially due to the effects of maternal hormones on the developing fetus in the last trimester. The same hormones that cause a mother’s breasts to enlarge and produce milk may affect your baby in the same way. Be sure to leave the area alone; don’t be tempted to pinch or squeeze the breasts if you notice milk production.
Most breast swelling is benign, but if you notice that the area around the breast is red or warm to the touch, be sure to pay the doctor a visit. Rarely, the breast can develop mastitis, an infection of the breast tissue.
Reviewed by Dr. Sara Connolly, December 2018