Trend analysis and socio-economic differentials in infant mortality in the Southern Health Board, Ireland (1988-1997).

The objective of this paper is to examine trends in infant mortality (IMR) and low-birth weight (LBW) in the Southern Health Board (SHB) area and to investigate the relationship between IMR and social and economic factors. IMR data were obtained from the Central Statistics Office (CSO) over a 10-year period (1988-1997). Social deprivation was measured using the Small Area Health Research Unit (SAHRU) Deprivation Index, which consists of five census-based indicators; unemployment, low social class, car ownership, rented accommodation and overcrowding. During the 10 years, 556 infants died, 380 deaths (68%) occurring in the neonatal period and 176 (32%) in the post-neonatal period. There was a downward trend in IMR throughout the study period, from 11.3 in 1988 to 4.0 in 1997 (p < 0.001). The IMR in Cork City was higher than the rate in the SHB area as a whole (p = 0.0001). Congenital anomalies accounted for 34% of neonatal deaths. Sudden infant death syndrome (SIDS) and congenital anomalies accounted for 45% (79/176) and 22% (39/176) of postnatal deaths, respectively. Only 7% of all district electoral division (DED's) in the SHB were classed in the most deprived SAHRU Deprivation Index category (level 5). Yet, almost half (43%) of the DED's in Cork City were level 5 compared to only 1% in Cork County and 2% in Kerry. Despite significant overall improvements in infant mortality in the SHB, infants born into the lower socio-economic area (Cork City) continue to experience higher relative risks of mortality in comparison with those born in the higher socio-economic areas. Further investigation into the apparently divergent socio-economic patterns of infant mortality within the SHB is necessary.