User:Mr. Ibrahem/Linea nigra

Linea nigra, also known as the pregnancy line, is a line of increased pigmentation seen on the abdomen during pregnancy. It is typically one centimeter (0.4 in) wide, brownish to blackish, and extends vertically in the midline from the pubis to the belly button. Variably, it may extend to the upper abdomen. In first pregnancies, onset is generally in the 3 month; however, it may appear earlier in subsequent pregnancies. It is associated with darkened patches on the cheek and darkened nipples.

The underlying mechanism is unclear but is believed to involved increased estrogen resulting in increased formation of melanin. Diagnosis is based on appearance. No specific treatment is required and it generally fades in the year of childbirth. The degree of pigmentation can be lessened by either avoiding sun or using sunscreen on the area.

Most pregnant women (>90%) are affected to some degree. Those with darker skin are generally more affected. Up to 30% of people on birth control pills may develop the condition, as may children and males. The term is from the Latin for "black line".