Linea nigra (Latin for "black line"), colloquially known as the pregnancy line, manifests as a linear area of heightened pigmentation frequently observed on the abdominal region during

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

. Typically spanning approximately one centimeter (0.4 in) in width, this brownish streak extends vertically along the midline of the

abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

, spanning from the pubis to the umbilicus. Variably, it may traverse from the pubis to the upper abdominal region. For pregnant women, the emergence of linea nigra is attributed to an increased production of

melanocyte-stimulating hormone The melanocyte-stimulating hormones, known collectively as MSH, also known as melanotropins or intermedins, are a family of peptide hormones and neuropeptides consisting of α-melanocyte-stimulating hormone (α-MSH), β-melanocyte-stimulating ...

by the

placenta The placenta (: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas, and waste exchange between ...

. This physiological phenomenon is concomitant with the occurrence of

melasma Melasma (also known as chloasma faciei,James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. . or the mask of pregnancy when present in pregnant women) is a tan or dar ...

and darkened nipples. Individuals with lighter skin pigmentation tend to exhibit this phenomenon less frequently in comparison to those possessing darker pigmentation. It is typical for the linea nigra to fade and dissipate within several months following childbirth. Although predominantly associated with pregnancy, it can manifest in people of either sex and all ages. Beyond the gestational context, its prevalence is found to be uniformly elevated in either sex during the ages of 11 to 15. This is potentially attributable to hormonal fluctuations characteristic of

puberty Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a female, the testicles i ...

. After age 15, the prevalence of the linea nigra declines. Particularly in postpubescent people, it often serves as an indicator of elevated benign

estrogens Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three ma ...

. The prevalence of this phenomenon drops below 10% following the age of 30. Furthermore, its appearance may ensue after rapid weight gain over a short interval. It could also rarely serve as an indicator of underlying hormonal imbalances, genetic disorders,

malignancy Malignancy () is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not ...

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

, or even fungal infections.

Additional images

File:Breastfeeding 6 day old twins.jpg, Woman nurses twins six days after birth. The linea nigra is still visible. File:Cesarean section scar and linea nigra.JPG, A

caesarean section Caesarean section, also known as C-section, cesarean, or caesarean delivery, is the Surgery, surgical procedure by which one or more babies are Childbirth, delivered through an incision in the mother's abdomen. It is often performed because va ...

scar A scar (or scar tissue) is an area of fibrosis, fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other Organ (anatomy), organs, and biological tissue, t ...

(horizontal red line) and linea nigra visible on a 31-year-old woman seven weeks after

childbirth Childbirth, also known as labour, parturition and delivery, is the completion of pregnancy, where one or more Fetus, fetuses exits the Womb, internal environment of the mother via vaginal delivery or caesarean section and becomes a newborn to ...

. File:Linea nigra line 2016.jpg, Linea nigra in darker skin

Additional images

See also

References