Preterm birth is a disease that seriously affects the outcome of perinatal infants.At present，the cause of the preterm birth is unclear.Most research data confirm that preterm labor has high risk factors，including the history of preterm labor，history of pregnancy with medical diseases，history of pregnancy complications，advanced pregnancy，low BMI，obese pregnant women，and malnutrition，etc.Identifing high-risk factors early is the key to preventing preterm birth.The key way to reduce the incidence of preterm labor is to identify high-risk factors by asking about medical history in the peripregnancy and early pregnancy.