Prenatal care in the United States, 1969--1975.
D003710:Demography; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008423:Maternal Age; D011247:Pregnancy; D011295:Prenatal Care / Q000639:trends; D012959:Socioeconomic Factors; D014481:United States