Staying up late during pregnancy usually does not lead to fetal malformations, but staying up late on a regular basis can affect the health of pregnant women and make them prone to fatigue. The causes that may easily cause fetal malformation include: exposure to radiation, as well as chemicals, pesticides and certain drugs in early pregnancy, long-term heavy alcohol consumption; infection with certain microorganisms during pregnancy, such as rubella virus, cytomegalovirus, herpes simplex virus, toxoplasma virus, syphilis, etc.; poor blood sugar control during early pregnancy in pregnant women with high blood sugar, as well as folic acid deficiency, in addition to genetic factors. Therefore, it is recommended to conduct pre-pregnancy check-ups and to get pregnant after curing certain diseases; to start taking folic acid in the first trimester of pregnancy and to conduct prenatal consultation for high-risk pregnant women; to have regular maternity check-ups after pregnancy, to avoid exposure to bad environment and drugs, to quit drinking and smoking; to consult a doctor if medication is needed to avoid improper use of medication affecting the fetus.