Epidemiologic approaches to the evaluation of obstetrical innovations.
D001724:Birth Weight; D002986:Clinical Trials as Topic; D005260:Female; D005313:Fetal Death / Q000453:epidemiology; D006306:Health Surveys; D049673:History, 20th Century; D006801:Humans; D007226:Infant Mortality; D009774:Obstetrics / Q000379:methods*; D010500:Perinatology / Q000266:history / Q000379:methods* / Q000592:standards; D011247:Pregnancy; D011248:Pregnancy Complications / Q000401:mortality; D011787:Quality of Health Care; D012959:Socioeconomic Factors; D014481:United States