There are various causes of fetal malformation, including genetic factors, maternal factors, external factors, etc., which can be caused by a single cause or a combination of factors. 1, genetic factors: common recessive and dominant genetic diseases of both parents, inbred marriage, etc., can lead to fetal chromosomal abnormalities, Down’s syndrome, there is no cure, and the survival rate of newborns is low; 2, maternal factors: mainly pregnancy Hypertension, gestational diabetes and other combined diseases can cause fetal developmental abnormalities; or long-term improper sleeping position, fetal intrauterine hypoxia can lead to abnormal brain development; 3, external factors: including pollution gas, X-rays, drugs, tobacco and alcohol, bacterial or viral infections, heavy metals, etc., these substances can be absorbed by the mother and transferred to the placenta, which can be ingested by the fetus and lead to fetal abnormalities. This causative factor causes different kinds of malformations, which can be mild or severe, such as cleft lip, digestive tract malformation, limb defect, brain defect, etc. Some of them have a high survival rate and can be treated after birth. Pregnant women should do a good preparation check during pregnancy, pay attention to their own condition, follow the doctor’s instruction before applying drugs, stay away from places with more serious pollution, avoid exposure to radiation, tobacco, alcohol, drugs and other substances, sleep on the left side as much as possible, and can alternate between left and right to avoid pressure on the fetus.