A: I wish I had a magic cure for them. Despite the claims of many advertisers, you can't really prevent stretch marks. Most pregnant women—between 75 and 90 percent—develop them on their abdomen, breasts, hips or thighs. However, a small percentage of lucky individuals seem genetically endowed to be stretch mark-free.

Stretch marks occur in the middle layer of our skin, called the dermis. It's likely that a combination of mechanical factors—rapid skin stretching—and hormonal factors cause stretch marks to occur. Rapid growth and skin stretching may cause the breakdown of small connective fibers in the dermis. Additionally, hormone changes, such as increases in estrogen, relaxin and adrenocortical hormones, can contribute to skin changes.

Initially, stretch marks may appear reddish or purplish and have a slightly different texture than the rest of your skin. Over time these tend to fade in color and flatten. Some studies have indicated that stretch marks are more common in younger moms, women with higher weight gain during pregnancy and women with larger babies.

While you can't change your genetics, the best way to avoid additional stretch marks is to minimize unnecessary weight gain, eat a healthy diet and exercise regularly. Eating a healthy diet replete with fruits, vegetables and healthy greens will help your skin be its healthiest, and may help your skin minimize changes.

Using a lotion will help with overall skin dryness and may feel good, but over-the-counter creams have not been shown to prevent or improve the appearance of stretch marks. Two studies tested special creams during pregnancy. One reported fewer stretch marks in women randomly assigned to use a cream containing Gotu Kola extract, vitamin E and collagen hydrolysate. Another reported beneficial results from massaging an ointment of vitamin E, panthenol, hyaluronic acid and elastin during pregnancy. While these products did show some benefit in controlled studies, these preparations are not commonly available.

It may take a year after your pregnancy for your stretch marks to become less noticeable. If you're bothered by them and are no longer pregnant, there are some treatments that may minimize their appearance. Such treatments are expensive and can be administered by a dermatologist. They include creams with Retin-A (which cannot be used in pregnancy), microdermabrasion and laser therapy.