What causes linea nigra?
Your skin, like the rest of your body, goes through some changes during pregnancy. It stretches to accommodate your growing belly and breasts, and it may change colour.
Most pregnant women notice darker patches of skin on their face, especially women who already have dark hair or skin. These patches of skin are called the “mask of pregnancy.”
You may also notice other areas of your body getting darker, like your nipples. If you have any scars, they might become more noticeable. Freckles and birthmarks may become more obvious, too.
These colour changes happen because of the hormones estrogen and progesterone, which your body produces in larger amounts to help your baby develop.
Estrogen and progesterone stimulate cells called melanocytes in your skin, causing them to produce more melanin, the pigment that tans and darkens your skin. Increased melanin production is what makes your skin change colour during pregnancy.
At some point during your second trimester, you may notice a dark brown line running down the middle of your abdomen, between your belly button and pubic area. This line is called the Linea Alba. You’ve always had it, but before your pregnancy it was too light to see.
When melanin production increases during pregnancy, the line gets darker and more obvious. Then it’s called the Linea Nigra.