Effect of prenatal care on infant mortality rates according to birth-death certificate files.

Infant mortality has decreased nationwide; however, our national rates still log behind those of other industrialized countries, especially the rates for minority groups. This study evaluates the effect of prenatal care and risk factors on infant mortality rates in Chicago. Using linked infant birth and death certificates of Chicago residents for 1989-1995, a total of 5838 deaths occurring during the first year of life were identified. Birth certificate variables, especially prenatal care, were reviewed. Variables were compared by stratified analysis. Pearson chi 2 analysis and odd ratios (ORs) were computed. Infant mortality rate (IMR) in Chicago decreased from 17 in 1989 to 12.6 in 1995 (P < .0001). Some factors increased IMR several fold: prematurity (OR 17.43), no prenatal care (OR 4.07), inadequate weight gain (OR 2.95), African-American ethnicity (OR 2.55), and inadequate prenatal care (OR 2.03). Compared with no care, prenatal care was associated with lower IMR; however, early care was associated with higher IMR and ORs than later care. These results demonstrate prenatal care is associated with lower IMR; however, compared with late prenatal care, early care does not improve IMR. Further studies should evaluate whether improving the quality of care improves IMRs.