Linea nigra

Linea nigra (Latin for "black line"), often referred to as a pregnancy line, is a linear hyperpigmentation that commonly appears on the abdomen.[1] The brownish streak is usually about a centimeter in width. The line runs vertically along the midline of the abdomen from the pubis to the umbilicus, but can also run from the pubis to the top of the abdomen.[2]

Linea nigra as seen in a pregnant woman

For pregnant women, linea nigra is attributed to increased melanocyte-stimulating hormone made by the placenta,[3] which also causes melasma and darkened nipples. Fair-skinned women show this phenomenon less often than women with darker pigmentation.[4] Linea nigra typically disappears within a few months after delivery.

Although linea nigra is rarely discussed outside pregnancy, males and females of all ages may have it. Except in pregnancy, both genders have highest and equal prevalence of linea nigra from age 11 to 15. This increase in prevalence could be the result of hormonal changes during puberty. After age 15, the prevalence of linea nigra in males declines. The prevalence for both genders drops to below 10% after age 30.

Additional images
  • Woman nurses twins 6 days after birth. The linea nigra is still visible.
  • A Cesarean section scar (horizontal red line) and linea nigra visible on a 31-year-old woman 7 weeks after childbirth.

See also

References
  1. Okeke, Linus Ikechukwu; George, Adekunle Olufemi; Ogunbiyi, Adebola Olufunmilayo; Wachtel, Mitchelle (November 2012). "Prevalence of linea nigra in patients with benign prostatic hyperplasia and prostate carcinoma". International Journal of Dermatology. 51: 41–43. doi:10.1111/j.1365-4632.2012.05564.x. ISSN 0011-9059. PMID 23210957.
  2. She Knows Network: "What's that line? All about linea nigra" Archived 2008-02-20 at the Wayback Machine
  3. Heffner, Linda (2010). The Reproductive System at a Glance. Wiley-Blackwell. pp. 51. ISBN 978-1-4051-9452-5.
  4. Pregmed, Editor (2014-11-15). "Linea nigra and pregnancy". Pregmed. Retrieved 22 February 2015.

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