By the way of investigation on the type of questions and answers,looking up the medical history and interview differently,the authors investigated 486 parturients who had delivered in two district?level MCH hospitals.

• 方法：以调查问卷、查阅病例和个别访谈的形式调查了在北京市2所区级妇幼保健院分娩的产妇共486例。