What Is Linea Nigra?
Linea nigra, also known as pregnancy line, is a physiologic hyperpigmentation seen during pregnancy. During pregnancy, a dark, vertical line develops on the stomach. This line generally develops during the first trimester of the pregnancy. This line runs down the middle of the stomach and abdomen and can be an early indication of pregnancy. It might extend toward the abdomen but usually runs from the belly button to the pubic region. As the pregnancy progresses, the linea nigra may become darker, particularly noticeable in those with darker skin tones. However, there is no need for medical treatment because linea nigra poses no risk to either the mother or the unborn child.
What Is the Purpose of Linea Nigra?
The purpose of the linea nigra is unknown. Some people have hypothesized that the deeper color aids a nursing newborn in navigating to the mother's breasts. There are numerous tales concerning the linea nigra that one might hear, but none of them have been confirmed.
What Causes Linea Nigra?
Pregnancy-related hyperpigmentation, including linea nigra, is caused by placental hormones, metabolic variables, and immunological factors.
Estrogen's and progesterone's combined effects lead to an increase in melanin production. Estrogen activates intracellular estrogen alpha and beta receptors present in the skin. This prompts melanocytes (cells in the skin and eyes that secrets the melanin pigment) to produce more melanin. As a result, melanin is accumulated in the epidermis (skin’s outer layer) and is taken up by dermal macrophages (immune cells present in the skin’s inner layer, dermis). Additionally, the placenta creates bioactive sphingolipids that activate tyrosinase and other melanogenic enzymes and proteins.
Who Gets Linea Nigra?
More than 90 % of pregnant women experience linea nigra, which frequently coexists with the darkening of the nipples, areola, and genital regions. In addition, compared to women with fair skin, darker complexions exhibit more obvious and frequent pregnancy-related hyperpigmentation.
Research with 1550 individuals from Nigeria reported the following:
-
92 % of pregnant women had linea nigra, compared to 16 % of non-pregnant women.
-
About 80 % of males older than 50 with benign prostatic hyperplasia (a condition where the prostate glands become enlarged) or prostate cancer had linea nigra.
What Are the Clinical Features of Linea Nigra?
The clinical features of linea nigra are as follows:
-
The linea nigra is a vertically extending line of hyperpigmentation that runs along the middle of the abdomen.
-
Linea nigra typically reaches the umbilicus (the belly button) from the symphysis pubis (the cartilaginous joint between the pubic bones). But, it can go much higher up to the lowest point of the sternum (bone in the breast region).
-
The color of hyperpigmentation can be anything from light brown to grayish black. After being in the sunlight, it could become darker.
-
Linea nigra typically has a width of 1 cm (centimeter), and it is the same width all the way through. However, during pregnancy, the linea nigra might get wider and more intense.
When Does Linea Nigra Appear?
Linea nigra appears during pregnancy, but it does not show up until the hormone levels in the body increase substantially. In most people, the linea nigra begins to darken considerably to become noticeable in the second trimester or at about 20 weeks. Before pregnancy, the linea nigra is present as linea alba or the 'white line.'
When Does Linea Nigra Go Away?
After delivery, the linea nigra will diminish as the hormone levels get back to normal. It takes weeks or months for the fading to occur gradually. It may not go away completely or take a very long time.
How Is Linea Nigra Diagnosed?
Linea nigra is detected clinically, just like other physiological changes associated with pregnancy. Therefore, no additional imaging studies or tests are required.
What Is the Differential Diagnosis of Linea Nigra?
Occasionally, other types of localized hyperpigmentation may be taken into account when determining the linea nigra's differential diagnosis. These include the following:
-
Cafe au lait macules (patches or macules that are well-defined, pigmented, and range in color from light to dark brown).
-
Post-inflammatory hyperpigmentation (it is an acquired hyperpigmentation that occurs following skin inflammation or damage).
-
Flagellate hyperpigmentation (pigmentation occurring as a complication of systemic Bleomycin therapy).
-
Melanocytic nevus (moles).
-
Seborrheic keratosis (noncancerous skin growth that is pigmented).
-
Lentigines (pigmented flat spots that occur due to sun exposure).
-
Certain skin infections.
Does Linea Nigra Require Any Treatment?
There are no medical treatments for linea nigra. The linea nigra has no negative effects on pregnancy or fetal growth. Therefore, no medical intervention is necessary. However, women who have this condition should stay away from the sun as it could make the line on their abdomen to become darker. Wearing sunscreen may be useful as UV (ultraviolet) rays from the sun can darken the color of linea nigra.
According to certain research, folic acid prevents the development of linea nigra. Leafy green vegetables, oranges, and whole wheat bread are just a few examples of foods rich in folic acid. Doctors do not suggest applying medications, topical ointments, or other skin-bleaching chemicals while pregnant. After the baby is delivered, using a bleaching lotion might be a possibility, but only if the mother is not breastfeeding.
Can Linea Nigra Be Prevented?
No, linea nigra cannot be prevented because the line appears due to hormonal changes that occur during pregnancy. Moreover, the line fades away soon after pregnancy when the hormone levels return to normal range.
What Is the Prognosis of Linea Nigra?
Linea nigra is not a medical condition or a symptom of any disease, and it is a normal occurrence experienced by most women during pregnancy. So there is no need to worry about this line's appearance. After childbirth, the linea nigra often gradually fades, but some women can develop prolonged hyperpigmentation. Additionally, it might come back during subsequent pregnancies.
Conclusion:
Linea nigra is one of the many physiologic changes that occur during pregnancy. A linea nigra is a Latin phrase that means black line. Pregnancy leads to linea nigra because the hormones modify the color of the skin. The good news is that after delivery, the linea nigra lightens, and the hormone levels return to normal. Generally, linea nigra does not cause any harm and does not require any treatment. However, it is advised to consult a doctor if the linea nigra is causing esthetic and other concerns.
