Behavioural outcome of school-age children after prenatal exposure to coumarins

In utero exposure to coumarin derivatives may affect the development of the central nervous system of the child, irrespective of the period of exposure in pregnancy. Little is known about effects on development in the long term. The aim of the present study was to determine whether prenatal exposure to coumarins affects behavioural outcome in children at school age. Behavioural outcome was assessed in a cohort of 305 exposed children, aged 7-15 years. Findings were compared with those in a cohort of 263 non-exposed controls, matched for sex, age, and demographic region. Behaviour was rated by parents and teachers using standardized questionnaires: the Groningen Behaviour Checklist Family situation (GBF) and the Groningen Behaviour Checklist School situation (GBS), respectively. The findings of the GBF were supported by the results of the GBS, filled in by teachers who were blind for the exposure status of the child. In comparison to the non-exposed children, the coumarin-exposed children scored lower on the cluster 'positive task orientation' (GBF P<0.05, GBS P<0.01), they scored higher on 'emotional instability' (GBF P<0.001, GBS P<0.05), and they had more problems on the social clusters (P<0.01). Based on the results of both questionnaires, we conclude that behavioural development may be negatively influenced in school-age children after in utero exposure to coumarins, leading to less favourable task-oriented and social-emotional behaviour. However, the frequency of clinically relevant 'problem behaviour' (GBF) was not increased in relation to coumarin exposure, the odds ratio was 1.2 (CI(95) 0.7-1.8).