Everyone has a line called the linea alba (“white line” in Latin) that usually isn’t noticeable. This line runs vertically from the breastbone to the pubic area and down the middle of the abdomen.
During pregnancy, this line can darken, causing a visible vertical line from the belly button to the pubic area, or sometimes the entire length of the abdomen. This is called the linea nigra (“black line”). It often correlates with changes in pigmentation during pregnancy such as the darkening of areas that already have more pigmentation like the nipples and areola.
Linea nigra is typically noticed in the second trimester.
What Causes Linea Nigra?
Hyperpigmentation in pregnancy is caused by increased melanin production by the melanocyte skin cells, stimulated by pregnancy hormones, including higher levels of estrogen, and likely progesterone or a melanocyte-stimulating hormone (MSH).
According to one study, linea nigra is the most common pregnancy skin change.
Melanin (the pigment that darkens skin) already exists in greater quantities in some areas of the body. The increase in melanin production during pregnancy can cause these areas to darken. Most commonly, hyperpigmentation is noticed in:
Nipples Areola Linea alba (leading to linea nigra) Genital area Face (called melasma or the “mask of pregnancy”) Neck Existing scars, freckles, and birthmarks
The intensity of the hyperpigmentation may be related to:
Environmental factors (such as exposure to sunlight) Diet Intake of some drugs Preexisting conditions (such as hyperthyroidism) Genetic predisposition
What Is the Purpose of Linea Nigra?
An old wives’ tale claims the gender of the baby can be determined by analyzing the length of the linea nigra. Though you may hear this from people during pregnancy, it is not backed by science and not at all reliable.
One theory some experts believe to be likely is that linea nigra—along with hyperpigmentation of the nipples and areola—provides a visual “map” of sorts to help a newborn baby find its way to the breast after birth.
How Is Linea Nigra Treated?
Treatment for linea nigra isn’t medically necessary. It doesn’t affect the pregnancy, and it almost always fades or goes away entirely in the months after birth.
People who dislike the look of linea nigra may try ways to reduce the intensity of the line, including with:
Folic Acid: Folic acid from foods such as leafy green vegetables, oranges, and whole wheat bread may reduce the formation of linea nigra. Sun Protection: The sun can darken linea nigra. Cover up, use a good broad-spectrum sunscreen, or stay out of the sun. Creams and bleaches: Cosmetic lightening agents can be used after pregnancy if not breastfeeding (they are not safe during pregnancy or while breastfeeding), but they are usually not effective or recommended.
A Word From Verywell
Linea nigra is a common and harmless form of hyperpigmentation seen in pregnancy. While it is sometimes quite noticeable, it is nothing to worry about and usually fades away in the months after the baby is born.
Physiologic changes of pregnancy: A review of the literature. International Journal of Women’s Dermatology,
Volume 3, Issue 4. doi:10.1016/j.ijwd.2017.09.003
