Pregnancy can do weird and wonderful things to your body. Your breasts and belly enlarge, your blood flow increases, and you begin to feel movements from deep inside.

Around the middle of your pregnancy, you may notice another unusual change: a dark line running down the front of your abdomen. It’s called the linea nigra, and it’s no cause for alarm.

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 color.

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 color 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 color 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.

Linea nigra isn’t harmful to you or your baby, so you don’t need medical treatment.

Some people believe that the linea nigra could send a signal about your baby’s gender. They say that if it runs to your belly button, you’re having a girl, and if it keeps going all the way to your ribs you’re due for a boy. But there isn’t any science behind the theory.

Soon after your baby is born, the linea nigra should start to fade. In some women, though, it may never completely disappear. And if you get pregnant again, expect to see that line reappear.

If the line doesn’t go away after pregnancy and its appearance bothers you, ask your dermatologist about using a skin bleaching cream. That may help the line fade more quickly.

Don’t use a bleaching cream during your pregnancy or while you’re breastfeeding, because it can be harmful to your baby.

If the line really bothers you during pregnancy, try concealing the line with makeup until it fades.

Be sure to wear sunscreen whenever you expose your belly and other areas of your skin to the sun. Sun exposure can make the line even darker.

Linea nigra happens during pregnancy because your hormones trigger color changes in your skin. It’s not something to be worried about and usually fades after you give birth.