Melasma is so common during pregnancy that there is a separate name for the condition: chloasma. It's also commonly referred to as the "mask of pregnancy" [source: Merck].
During pregnancy, a woman's levels of the hormones estrogen and progesterone rise, which can sometimes increase pigment production in their skin cells. Since many birth control pills contain hormones, women who take them are also more susceptible to melasma, as are women who use hormone therapy replacement during menopause. Melasma patches on the face, forearms and neck should fade within a few months of giving birth, but they are likely to return each time a woman becomes pregnant [source: American Academy of Dermatology: Melasma].
If you're pregnant, you should take the same steps as anyone else to protect yourself from the sun's rays in order to prevent and treat melasma. However, don't use skin-bleaching creams or special treatments until after you give birth and finish nursing. Having splotches on your face for nine months may be frustrating, but it's better to try and use some type of concealer to hide the effects of melasma. Don't use any new products that you haven't already tested on a small area of your skin.
During pregnancy, another effect of melasma may be the darkening of areas that are normally a little darker than other parts of the body. These include freckles, scars and the skin around your genitals. You may also notice a dark line down the center of your abdomen -- that's called the linea nigra, and it should also fade a few months after you give birth.
Whether you're pregnant or not, the best way to protect yourself from melasma and from many skin conditions is to stay out of the sun. For more information, move on to the next page.