After pregnancy, it is normal for the underarms of pregnant women to darken, which is the pigmentation of pregnant women. After pregnancy, the color of pregnant women’s breasts and nipples will become darker; a black line will appear from the abdomen to the pubic bone; chloasma will appear on the forehead, nose and cheeks of pregnant women; and pregnant women’s armpits and inner thighs will sometimes become darker and blacker, all due to the endocrine changes of pregnant women after pregnancy. After pregnancy, pregnant women have a vigorous metabolism, hypersecretion of sweat glands, more sweating and more oil. The appearance of chloasma and hyperpigmentation are related to hormonal changes after pregnancy. After a pregnant woman gives birth, the color will gradually fade or disappear. Strong direct ultraviolet light should be avoided as much as possible during pregnancy.