Postpartum hair loss generally begins three months after childbirth and is a normal physiological phenomenon. In medicine, it is also known as telogen effluvium postpartum. The main reason for hair loss is related to changes in estrogen levels in the body after pregnancy. During pregnancy, the increased levels of estrogen slow down the rate of hair loss and extend the life of hair. However, after giving birth, hormone levels gradually decrease and the hair loses hormonal support, leading to hair loss. This condition typically starts around three months postpartum and can gradually improve around six months after childbirth.