Pregnancy and weight gain are the two major causes for stretch marks. When your skin is stretched to maximum capacity, your skin’s elastic fibers and collagen breaks down and the ruptured middle layer tissue can then be seen through the thinned outer layer of skin.
Before giving birth, women will experience a stretching of the skin and underlying tissue in their abdomens. More often than not, constant erratic cravings have these poor mothers eating far more than they would like to, causing extra weight gain. Not only does the skin start stretching, but other changes take place as well.