The darkening of the belly button during pregnancy is a normal physiological phenomenon and does not require special treatment. After pregnancy, the pregnant woman’s body will increase the secretion of melanocyte stimulating hormone, coupled with the increase in estrogen and progesterone, can promote the increase in melanin production, which will lead to pregnant women in the areola, umbilicus, vulva and other places of hyperpigmentation, which is a normal physiological phenomenon, so when the belly button becomes black after pregnancy is normal, and can be gradually recovered after delivery. With the increase of the uterus after pregnancy, some pregnant women will be due to the abdominal wall skin tension increases, making the skin elastic fiber fracture and the formation of stretch marks, with the increase of pregnancy weeks will also cause low back pain, lower limbs or perineal varicose veins, lower limb edema, constipation and other symptoms, can be given under the guidance of the doctor to give appropriate treatment.