The darkening of the armpits of women during pregnancy is mostly related to the increase of hormone levels in the body and physical factors: 1, mainly due to the increase of estrogen and progesterone in the body after pregnancy, as well as the increase of melanocytes, which will promote the appearance of pigmentation in places with pubic hair, i.e., the expression of darkening, such as the armpits or vulva and other parts, is a normal physiological phenomenon. 2, in a few cases, there are also individual women and genetic factors have a certain relationship. In a few cases, there is also a certain relationship between the individual female physique and genetic factors, so when women find the armpit darkening during pregnancy, women should not be overly nervous, keep the armpit local cleanliness and hygiene, avoid excessive local humidity, can normally eat more fresh vegetables and fruits, maintain a regular lifestyle, regular obstetric check-ups, will not cause adverse effects on the development of the pregnant woman herself and the fetus. The impact will not be detrimental to the development of the pregnant woman and the fetus.