Inclusion Criteria:  The pregnant woman is born at a gestational age of 24-40 weeks; The pregnant woman has a single child; Regular obstetric examination during pregnancy with complete obstetric examination data was diagnosed as premature rupture of membranes (PROM).  Exclusion Criteria:  Pregnancy complicated with medical and surgical diseases, such as thyroid dysfunction and chronic hypertension; Insufficiency of vital organ function or complicated tumor; Pregnant women with other pregnancy complications besides PROM, such as preeclampsia, etc.; Neonates had major congenital malformations (congenital anal atresia, congenital biliary atresia, congenital heart disease and so on, whether prenatal suspicion or diagnosis postpartum) Neonatal septicemia, hemolytic disease or other diseases affecting bilirubin metabolism.