Maternal risk factors for cause-specific stillbirth and neonatal death

Background: To study specific effects of four maternal risk factors: age, p arity, educational level, smoking, for specific causes of stillbirth and ne onatal death according to a previously described hierarchic classification. Methods. The study is based on 9,785 stillbirths or neonatal deaths among i nfants born in Sweden, 1983-1995 (n=1,412,754) and identified with various Swedish health registers. Statistical analysis is performed using Mantel-Ha enszel analysis. Results. Some risk factors, known from the literature, were confirmed and c ould be quantified. In addition. high parity was shown to increase the risk for death associated with multiple births (OR=2.49, 95% CI 2.07-3.01) and low educational level seems to be protective for such death (OR=0.75, 95% C i 0.60-0.93). If the infant is SGA, the risk for death is higher at high th an at low parity (1.70, 95% Ct 1.19-2.43, and 1.0, 95% CI 1.06-1.15, respec tively), Maternal smoking seems to aggravate the placental abruption becaus e the death risk in the presence of abruption increases when the mother smo ked (OR=1.74, 95% CI 45-2.08). Conclusions. The study shows that the groups of the classification system u sed (NICE) differ in their association with known risk factors for stillbir th and neonatal deaths and an analysis based on specific causes of death ca n therefore unravel risk factors hidden when total mortality is used. The c omputerized method of classification and the cause-of-death classification developed by us is clearly useful for such analyses which requires large ma terials.