Melasma is a skin condition that causes dark, discolored, blotchy patches on skin, most commonly on different areas of face. Melasma is otherwise referred to as the "mask of pregnancy" because it is ofter triggered by an increase in hormones in pregnant women. In pregnancy, a rise in estrogen and progesterone levels stimulates excess melanin production meaning that your skin may look darker. While melasma may be common among pregnant women, it isn't limited to them. According to American Academy of Dermatology, only 10% of people who get melasma are men.
If you suspect that you might have a "mask of pregnancy" try to avoid excessive sun exposure and other irritants that can damage your skin. In most cases, the discoloration due to melasma is temporary and disappears after delivery or after you finish breastfeeding. However, if the condition persists for a long time or if you notice something abnormal, it is always a good idea to see a dermatologist.