Stretch marks -- discolored lines that appear on the skin -- are caused when the skin is overstretched and the skin fibers break, allowing blood vessels underneath the skin to show. An estimated 50 to 80 percent of all people will experience stretch marks at some point in their lives, with many developing stretch marks on their breasts. While stretch marks have multiple causes, there are certain factors that increase a person’s likelihood of developing breast stretch marks.
Baby on Board
Pregnancy initiates many changes in a woman’s body, including increased breast size. The estrogen and progesterone hormones released during pregnancy cause breasts to swell and enlarge, which can stretch the skin on the breast causing stretch marks. While the most dramatic increase in these hormones occurs during the first trimester, a woman’s breast size will probably continue to increase throughout the entire pregnancy, and stretch marks may appear at any time. Additionally, many women experience a dramatic increase in breast size immediately following childbirth when the breasts fill with milk as part of the lactation process. This rapid breast enlargement can also cause stretch marks to develop.
Gaining More Than A Few Pounds
Stretch marks often appear in areas of the body that store fat, which include the breasts, hips and abdomen. As a person gains weight and their Body Mass Index increases, their breasts are likely to increase in size to accommodate the additional fat cells. This increase in size can tighten the skin, causing stretch marks to appear. Rapidly gaining weight over a short period of time increases the chance that stretch marks will develop because the skin has not had adequate time to adjust to the new size, whereas gaining weight slowly and gradually allows the skin more time to appropriately adapt to the stretching.
What Your Doctor Knows
Certain health conditions make people more prone to stretch marks. According to the University of Arizona Department of Surgery, 60 percent of people diagnosed with Cushing’s Syndrome -- an adrenal disease that causes the body to produce excess amounts of cortisol hormone -- notice an increase in stretch marks. This excess cortisol hormone released by the body causes a decrease in the body’s natural collagen that keeps the skin elastic and stretchable. Additionally, people who use corticosteroids to treat skin inflammations like eczema are at a higher risk for developing stretch marks. The corticosteroids function like the cortisol hormone does -- they break down the body’s collagen, decreasing the skin’s ability to stretch.
Blame Your Mom
Genetics contribute significantly to a person’s chances of developing stretch marks. Scientists have identified DNA genetic markers, passed from one generation to another, that are linked to the development of stretch marks. This hereditary connection means a woman whose mother or grandmother had stretch marks is predisposed to developing stretch marks herself. While these genes can put certain women at an increased risk for developing stretch marks, the presence of the genes does not guarantee that stretch marks will appear, and some women carrying these genes never experience stretch marks.