Melasma (chloasma) is a hyperpigmentation of the skin that commonly occurs in pregnancy. It is sometimes called a "pregnancy mask." In melasma, tan or brown patches appear on the face. Often, melasma will disappear after pregnancy. Sunlight may irritate melasma, so be sure to use proper sunscreen and other sun protection. Follow the links below to find WebMD's comprehensive coverage about how melasma is caused, what it looks like, how to treat it, and much more.