Pregnancy and weight gain are the two major causes of 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. As unattractive as this may be, it is an almost inevitable part of having a baby, since your fluctuating hormones alter your skin's ability to simply bounce back. Even so, there are home remedies and proper precautions for stretch marks that you can take to make these unsightly scars obsolete.