早产是围产儿死亡的主要原因之一，早产儿有15％死于新生儿期，约1/4留有神经或智力方面后遗症。因此，防治早产是围产期保健工作中一个重要的课题。一、早产的定义自末次月经第一日起，妊娠≥28周至＜37周终止者，为早产。二、早产的病因 Preterm birth is one of the major causes of perinatal death, with 15% of premature children dying in the neonatal period and about 1/4 with neurological or intellectual sequelae. Therefore, prevention and treatment of prematurity is an important issue in perinatal care. First, the definition of preterm menstruation From the first day of the last menstruation, pregnancy ≥ 28 weeks to <37 weeks termination, is premature. Second, the etiology of premature birth