Trends in prenatal cave use and low birthweight in southeast Brazil

Objectives. We investigated trends in prenatal care use and its association with low birthweight in a developing country. Methods. We examined data from 2 southeast Brazilian cohort surveys, 1 conducted in 1978-1979 and the other in 1994. Results. Socioeconomic inequalities in prenatal care use increased during the 15-year period of 1979-1994. Although prenatal care use increases paralleled increases in low birthweight rate during this period, having no prenatal care was associated with higher risk of low birthweight in both surveys. Inadequate prenatal care use was also associated with higher risk of low birthweight in 1978-1979 only. Conclusions. Increasing low birthweight rates among women who adequately used prenatal care may be causing a bias by reducing the estimates of the effect of inadequate prenatal care use on low birthweight rates.