Defects of the central nervous system in Finland: V. Multivariate analysis of risk indicators.

Based on the Finnish Register of Congenital Malformations a search was undertaken for associations between defects of the central nervous system [CNS] and various selected risk indicators. The study material consisted of 710 cases of CNS defects and their time-area matched pair controls. 259 cases of polydactyly and their controls were also compared with a view of demonstrating the possible biases introduced by the case-control method. The present report is a multivariate analysis of previously observed associations, and the linear logistic regression model was used for the elimination of confounding factors. Risk indicators remaining after the analysis were high maternal age, multipara with previous stillbirths and defective children, especially defects of the CNS. Maternal influenza, especially in combination with the intake of salicylates, was also associated with an increased risk.