Regional trend variations in infant mortality due to perinatal conditions in the Netherlands

Condensation: In the Netherlands, regional variations in trends in infant m ortality due to perinatal conditions (1984-1994) exist, which could not be explained by health care characteristics (i.e., place or supervision of del ivery and the presence of specialised neonatal care). The only sociodemogra phic factor that showed a consistent correlation with mortality was the per centage of Roman Catholic inhabitants of a region. Objective: To describe a nd explain regional variations in trends in infant mortality due to perinat al conditions. Study design: A mixed (geographical and temporal) ecological design has been used. Infant mortality due to perinatal conditions was def ined as mortality in the first year of life caused by diseases of the newbo rn period (chapter XV of the ICD-9). Trends in sex-adjusted mortality for t he period 1984-1994 as well as mortality levels at the start of this period were calculated using log linear regression. Linear regression was used to examine the association between mortality trends and starting levels on th e one hand and both health care and sociodemographic factors on the other. Results: Statistically significant variations in mortality trends were foun d between regions. The trends in the two Southern regions were found to dev iate significantly from the national trend. No strong association was found between mortality and each of the health care factors (i.e. place and/or s upervision of delivery and the presence of specialised neonatal care). The only sociodemographic factor that showed consistent results was the percent age of Roman Catholic inhabitants of a region: A higher percentage in 1985 was associated with a higher mortality in 1985 and a stronger mortality dec line during the period 1984-1994. This association could not be explained b y parity or the age of the mother. Conclusions: Regional differences in tre nds in infant mortality due to perinatal conditions in the Netherlands coul d not be explained by variations in health care factors. This is an importa nt finding as the Dutch system of obstetric care, that includes a considera ble number of home deliveries, has been subject to much debate. Further res earch that includes other causes of death and determinants is needed to unr avel the causes of the trend variations. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.