If you're pregnant, you'll need to step up your year-round sun protection during the summer, not only to prevent premature aging and skin cancer, but also to ward off melasma, or "the mask of pregnancy." Up to 70 percent of pregnant women will develop melasma (also called chloasma), dark patches of skin on the face that occur after sun exposure, the result of excess melatonin in the skin caused by surging estrogen levels. It's not the pregnancy glow women hope for, but it can be prevented, says Lisa M. Cohen, M.D., assistant professor of dermatology at Tufts University School of Medicine in Boston. "It's a good idea to stay out of direct sunlight between 10 a.m. and 3 p.m., to use a good sunscreen, and to wear protective clothing, including a wide-brimmed hat and long sleeves." Dr. Cohen advises using a sunscreen with SPF 15 or higher that blocks both UVA and UVB rays. One of the many products available is Coppertone's new Oil Free Faces, which provides SPF 30 broad-spectrum protection. The American Academy of Dermatology (AAD) suggests applying sunscreen 15 to 30 minutes before going outside and reapplying it every two hours, as well as immediately after swimming or strenuous activity, even if you're using a waterproof product.

If your best sun protection efforts don't keep you from developing melasma, you won't have to live with it forever. The condition usually fades within a few months of delivery, but if it doesn't, treatments such as hydroquinone or Retin A can even out skin tone, though neither of these are recommended during pregnancy. While some over-the-counter products use pregnancy-safe tea tree oil and kojic acid as bleaching agents, Dr. Cohen advises against using them, as they can have uneven results if not applied correctly. Melasma can also affect women who aren't pregnant: It can be caused by birth control pills, endocrine problems, or hormone fluctuations.

While it's normal for skin moles to darken during pregnancy, alert your doctor to marks or moles that change in size or shape or that start to itch or bleed. The American Cancer Society estimates that 87,900 people will be diagnosed this year with a form of skin cancer known as melanoma, so consider having an annual checkup by a dermatologist. (Even women who aren't at high risk for developing skin cancer can benefit from professional exams.) This month, many AAD members are offering free skin cancer screenings. Log on to the AAD website at www.aad.org or call 888-462-DERM to find a location near you.

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