Congenital defects and occupational factors. A comparison of different methodological approaches.

In a previous study of children with congenital CNS (central nervous system) defects (N = 120), it was shown that exposure had occurred more often among the study mothers than among their referents. In the present study this population, extended with a one-year material of parents of children with oral clefts (N = 102) and their referents, was analyzed in a conventional way concerning occupational factors. This procedure was carried out in order to determine whether information on occupational factors only would provide enough hints to confirm known information concerning exposure, which had been acquired with the more-detailed but laborious interview method. No significant differences were observed in a comparison between the study groups and their referents when work of the mothers outside the home during pregnancy was considered. According to the social class grouping, classes 3 and 4 appeared more often among parents of children with congenital CNS defects than among their referents. With respect to industrial classification, manufacturing and different community services occurred more often among mothers of children with congenital CNS defects and oral clefts than among their referents. Some clustering could be observed with regard to the occupations of the parents in the two study groups as compared to their referents. When the material was methodologically processed in the conventional way described, no obvious conclusions could be drawn about exposure.