Darkening of the underarms during pregnancy is a normal phenomenon, usually due to changes in hormone levels in the body, resulting in localized pigmentation and deposition of the phenomenon. During pregnancy, the level of androgens in the female body rises, which promotes the production of melanocytes, thus causing an increase in melanin, which is deposited in the armpits, and will show the phenomenon of darkening of the armpits. Not only the armpits, pregnant women’s nipples, abdominal midline, vulva and other parts of the body will also appear darkening phenomenon, usually pregnant women in the birth of the black parts will slowly return to normal. Darkening of the armpits during pregnancy may also have other conditions, it is recommended to consult a doctor in time to rule out abnormalities, if necessary, under the guidance of the doctor for symptomatic treatment. Pregnant women should also follow a regular routine, eat plenty of fruits and vegetables, and undergo regular checkups.