melasma causes
Melasma Causes. Melasma is usually caused by the sun, hormones in birth control pills, hormone replacement therapy, medications and pregnancy. When Melasma is caused by pregnancy it is called chloasma. In some women, when the skin is exposed to sunlight, brown blotches of excess pigment form due to the interaction with hormones or chemicals. Melasma is believed to be hereditary and woman with darker skin tones tend to be more at risk for this disorder.