In plain words
Linea nigra is a dark line that runs from the belly button down toward the pubic area. It shows up in many pregnancies, usually in the second half. Hormones increase pigment production in the skin, which makes the line darker. It is harmless. Some people see it only on the belly, and others see it on other areas too. Some people do not see it at all. The line often fades after birth, though it may stay faintly visible for a long time. Skin changes in pregnancy are common, and this is one of several. Sun exposure can darken it further. If a spot changes shape, color, or size, or bleeds, tell your provider. That is a reason for a skin check, not a sign of the line itself.
The deeper version
Linea nigra is hyperpigmentation of the , a midline band of epidermal melanin deposition driven by increased melanocyte-stimulating hormone and by the estrogen and progesterone effects of pregnancy. It is diagnosed by inspection and is one of the physiological skin changes of pregnancy, alongside areolar darkening, in centrofacial, malar, or mandibular patterns, striae, and spider angiomas from estrogen-driven vasodilation. Kroumpouzos and Cohen (2001) reviewed the dermatoses of pregnancy and described most of these changes as physiological. The clinical task is to separate benign pigment change from atypical nevi by standard dermatologic criteria. The controversy is limited, though people with a personal or family history of melanoma are often advised to have changing spots checked.
Where it comes up
- Skin in pregnancy: stretch marks, linea nigra, melasma, itchingPregnancy: Your Body
- Your changing body and how you feel about itPregnancy: Mind and Life
What mothers here say about linea nigra
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Sources
- Kroumpouzos G, Cohen LM — Dermatoses of pregnancy. Journal of the American Academy of Dermatology, 2001