The linea nigra is a dark, vertical line running down your belly. Also called the pregnancy line, it shows up in most pregnancies, but is more noticeable in women with dark skin or hair. The linea nigra appears because of high levels of hormones like estrogen and progesterone during pregnancy, which can make some areas of the skin look darker. After pregnancy, the line on the stomach will usually fade within a few weeks.
Why does the linea nigra appear?
The linea nigra’s appearance is related to higher-than-usual levels of hormones during pregnancy. Estrogen and melanocyte-stimulating hormone act on the cells that contain melanin, the pigment that gives your skin its color. It’s not well understood why these cells (called melanocytes) appear darker in some parts of the body and not others.
The linea nigra is just one of the ways that skin can change during pregnancy. Some women develop darker patches on their face called melasma or “mask of pregnancy.” Often, other pigmented areas of skin get darker. You may notice this on your areolas (the area around the nipples); your labia majora (the folds of skin around the vagina); and where your skin creases, such as by your armpits and where your legs meet your torso.
When does the linea nigra appear?
As hormone levels rise, a noticeable linea nigra develops, usually by the middle of pregnancy. In fact, this line on your belly was always there but wasn’t visible. That line is called the linea alba (white line). When it darkens, the linea alba becomes the linea nigra.