Linea nigra

File:Linea nigra.jpg

Linea nigra dark midline streak on a 22 weeks pregnant female.

File:Cesarean section scar and linea nigra.JPG

A Cesarean section scar (horizontal red line) and linea nigra visible on a 31 year old female 7 weeks after childbirth.

Linea nigra (Latin for "black line") is a dark vertical line that appears on the abdomen during about three quarters of all pregnancies. 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 xiphoid process.

It is a type of hyperpigmentation resulting from increased production of the pigment melanin thought to be caused by increased estrogen, the same process that causes the areolas to darken. Why this process of hyperpigmentation occurs on the midline of the abdomen is uncertain. Fair-skinned women show this phenomenon less often than women with darker pigmentation. Before it appears it may be more faintly visible as a white line.

Linea nigra tends to appear around the second trimester. After birth, the line fades slowly, but may never disappear entirely, and sun exposure may cause it to recur.

See also

• Chadwick sign
• List of cutaneous conditions

References

ar:خط أسود pl:Linea nigra