Pregnant women endure a wide range of symptoms and side effects. Some of them are uncomfortable and some might be perplexing, but most of them are essential for growing and supporting the new life. Expectant mothers who develop Montgomery's tubercles may find the tiny bumps annoying or mysterious, but they actually play an important role in preparing the breasts for nursing.
Montgomery's tubercles are raised bumps---12 to 15 on average---found within and encircling the areola of each breast. The bumps develop when sweat glands beneath the skin experience growth and increased production, making them more pronounced and noticeable.
The bumps are triggered by the hormones of pregnancy in preparation for breastfeeding the infant. They usually develop during the first trimester. As long as a woman's body is preparing to nurse or actively nursing a baby, the hormones associated with gestation and lactation will keep the glands hard at work, producing lubrication to protect and nourish the skin of her nipple.
Dr. William F. Montgomery was the first to document the presence of these bumps in pregnant and lactating women and to determine their cause and purpose. His publication, "An exposition of the signs and symptoms of pregnancy," documented his findings in 1837.