摘要: An analysis of United States birth certificate records for the calendar year 1977 indicated that women who failed to seek prenatal care were at increased risk delivery a low-birth weight infant, even after social factors considered. However, strength association, as well population impact, between antenatal and varied by group. Prenatal had greatest observed impact socially disadvantaged women, because their high overall infants. From these observations, it appears efficacy services is modified situation. As result, summary evaluations may underestimate true value certain groups.