Effect of prenatal care on infant mortality rates according to birth-deathcertificate files

Infant mortality has decreased nationwide; however, our national rates stil l lag behind those of other industrialized countries, especially the rates for minority groups. This study evaluates the effect of prenatal care and r isk 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 cert ificate variables, especially prenatal care, were reviewed. Variables were compared by stratified analysis. Pearson chi(2) analysis and odd ratios (OR s) were computed. Infant mortality rate (IMR) in Chicago decreased from 77 in 1989 to 12.6 in 1995 (P<.0001). Some factors increased IMR several fold: prematurity (OR 1 7.43), no prenatal care (OR 4.07), inadequate weight gain (OR 2.95), Africa n-American ethnicity (OR 2.55), and inadequate prenatal care (OR 2.03). Com pared with no care, prenatal care was associated with lower IMR; however, e arly care was associated with higher IMR and ORs than later care. These res ults demonstrate prenatal care is associated with lower IMR; however, compa red with late prenatal care, early care does not improve IMR. Further studi es should evaluate whether improving the quality of care improves IMRs.