Birth defect and risk factor surveillance in the northern and southwestern Netherlands

To survey the associations between several risk factors and birth defects, in order to detect potential new teratogens.

Data of the two Dutch European Registration of Congenital Anomalies (EUROCAT) registries collected before January 1, 1998 were used to perform chi2 tests for a large number of risk factors and birth defects. Defects caused by chromosomal or monogenic disorders were analyzed separately.

Cross-tabulations of 80 groups of birth defects with 303 risk factors were studied. Of these, 126 combinations had a p value under 0.05, and 34 had a p value under 0.001. Of these 34 associations, some are known in the literature, some were found before in the same databases and some were new associations.

This is a good method for generating new hypotheses for associations between risk factors and birth defects. It can be a start for new, more in-depth studies of potential teratogens.