The specific etiology of hyperemesis gravidarum is not yet completely clear, and may be related to genetic factors, physical factors, infectious factors, endocrine factors, and history of ectopic pregnancy. 1. Hereditary factors: since hyperemesis gravidarum is caused by abnormal development of fertilized eggs, it is related to the genetic heritage of the parents, and there are also some differences in the chances of hyperemesis gravidarum among different races. 2. Physical factors: the individual’s nutritional status and the age of pregnancy (greater than 35 and 40 years old, the incidence of significantly higher), may also affect the incidence of hyperemesis gravidarum. 3. Infectious factors: the formation of hyperemesis gravidarum may be related to viral infection. 4. Endocrine factors: ovarian insufficiency or ovarian function decline may also increase the incidence of hyperemesis gravidarum. 5. Because of the history of pregnancy: previous history of hyperemesis gravidarum, or miscarriage, ectopic pregnancy and other medical history is also a high-risk factor. There may be other reasons for the formation of hyperemesis gravidarum in the clinic, which need to be actively examined and treated in the hospital in order to prevent the occurrence of complications.