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Linea nigra
From Wikipedia, the free encyclopedia
Linea nigra (Latin for "black line") or línea negra (altered by influence of Spanish negra) refers to the dark vertical line that appears on the abdomen during pregnancy. The brownish streak is usually about a centimeter in width. The line runs vertically along the midline of the abdomen from the pubis to the xiphoid process - the bottom-most part of the rib cage in the center or tip of the sternum.
It is caused by pregnancy hormones that increase production of the pigment melanin, also known as hyperpigmentation. Why this process of hyperpigmentation occurs in a straight vertical line is uncertain. Fair-skinned women show this symptom less often than women with darker pigmentation[citation needed]. Before it appears it may be more faintly visible as a línea alba ("white line").
Línea negra tends to appear around the second trimester and may or may not disappear within a few months after birth. Some research suggests there may be a link between linea nigra and insulin. Supplementing the diet with folic acid is said to reduce the discoloration.
There is an old wives' tale associated with línea negra: if the línea negra runs to the navel, it's a girl, and if it goes all the way up to the xiphoid, it's a boy.