Socioeconomic correlates of infant mortality in Hong Kong, 1979-93.

Although Hong Kong's infant mortality is among the lowest in the world, there may still be subgroups in the population with unusually high and possibly avoidable mortality rates. We conducted an ecological study on the relationship between socioeconomic deprivation and infant mortality in Hong Kong by using government data from three periods: 1979-83, 1984-88 and 1989-93. The study population comprised all infant births in 65 modified districts in Hong Kong in the period 1979-93. Infant, neonatal and post-neonatal mortality rates (IMRs, NMRs and PNMRs) were used as the health indicators. An F score was derived from highly correlated socioeconomic variables by factor analysis and used as a summary index of socioeconomic status. In 1979-83, socioeconomic deprivation was found to be significantly associated with high IMRs and high NMRs in both sexes, while in 1984-88 this association was observed only in baby girls. None of the observed associations were significant in 1989-93. Overall, the territory's infant mortality rates fell from 10.2 per thousand live births in 1979-83 to 5.6 per thousand live births in 1989-93. Individual-based studies are needed to ascertain whether this apparent disappearance of the socioeconomic relationship with infant and neonatal mortality is real.