Declines in nonwhite and white neonatal mortality in Mississippi, 1975-80.

Linked birth and death records provided the population for an investigation of declines in nonwhite and white neonatal mortality rates (NMR) in Mississippi between 1975 and 1980. The effect of changes in the characteristics of women giving birth and in perinatal care on declining NMRs was analyzed. A decomposition of the difference in the 1975-76 and 1979-80 NMRs was performed to determine whether declines in NMRs were due to shifts in population characteristics or in characteristic-specific rates. Between 1975 and 1980, the NMR declined significantly by 1 death per 1,000 live births per year among nonwhites and by 0.8 per 1,000 among whites. Increases in the number of prenatal visits during the study period were associated with part of this decline, especially for nonwhites. The effect of rising use of prenatal care on NMRs was not, however, a result of shifts in the birth weight distribution. The decrease in NMRs was also associated with declining birth weight-specific rates; 75 percent of the decrease in rates was noted among low birth weight infants. Shifts in the distribution of birth weight and in maternal characteristics had little effect on declining NMRs. A strong commitment of the Mississippi State Board of Health to provide prenatal care to indigent women may be responsible for the large increases in use of prenatal care among Mississippi women. The decline in NMRs among low birth weight infants is likely linked to greater availability of specialized care for the sick neonate, although survival of these infants increased across the State, even where specialized care was not available.