Linea Nigra… Who Drew This Line On My Belly?!

Linea Nigra

We can’t say it enough: pregnancy has an effect on pretty much every part of your body. Your skin is not exempt from this rule.

You probably knew about some of the changes your skin would go through during pregnancy, such as the “pregnancy glow” or stretch marks. But, now, you are in your second trimester and you are seeing something a bit odd on your abdomen, right over your baby bump. It is a dark vertical line. What gives?

The line you are seeing is called the linea nigra, which is Latin for “black line.” It usually runs from just over your pubic bone up to your navel, but can go up to the top of your abdomen. In color, it varies from a tan that is slightly darker than the rest of your belly to a dark brown line. Generally, a linea nigra is about a centimeter wide.

Linea nigra occurs to three out of every four pregnant women. It less common in fair-skinned women and more common in olive-skinned women and women of color. It is also more likely to form if you lie out in the sun in your two-piece bathing suit.

This dark line is caused by the influence of one of your pregnancy hormones on your skin. Your placenta makes a hormone that stimulates melanocytes, which are the cells in your skin that manufacture melanin, the pigment that gives skin its color. This melanocyte-stimulating hormone is what also causes your nipples to darken and causes some women to develop melasma, the mask of pregnancy.

The linea nigra lies directly over another feature of your anatomy called the linea alba, which is Latin for “white line”. Everyone has a linea alba, but it is below the skin and not a structure of the skin itself. It is the vertical line of connective tissue between the two rectus abdominus muscles that run vertically directly down the middle of your abdomen. If you work out enough to have developed a six-pack, your linea alba is the central vertical line.

By the way, there is an old bit of pregnancy lore that says that the length of a linea nigra can predict the sex of your baby. If the line went no further up than your navel, you were going to have a girl. If it went up past your navel, you were going to have a boy.  There were lots of old wives’ tales like this before ultrasound was used to determine your baby’s sex. Most of them, and probably this one, weren’t very accurate.

What Should You Do?

Nothing. A linea alba is absolutely harmless and is nothing to worry about. If having a linea nigra bothers you, take comfort in the fact that it usually fades after your delivery. Do not use any kind of bleaching cream or skin lightener, especially not during your pregnancy.

But I’m Not Pregnant!

A linea nigra can sometimes develop in women who are taking birth control pills that contain estrogen. However, if you are not pregnant or not taking birth control pills, and have developed a linea nigra, you might want to check it out with your healthcare provider. Changes in pigmentation can be due to medical conditions such as Addison’s disease or polycystic ovary syndrome.

Valerie DeBenedette
Valerie DeBenedette is an experienced health and medical writer who lives about an hour north of New York City with a dog that is smaller than her cat. Her work has appeared in magazines, newspapers, newsletters, and on websites. She is a member of the National Association of Science Writers.

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