Is clonidine a behavioural teratogen in the human?

Twenty-two children prenatally exposed to clonidine and no other hypotensive drugs were compared at a mean age of 6.3 +/- 1.6 years to a non-exposed control group, matched for degree of maternal hypertension, sex, birthweight and gestational age. There were no differences in head circumference, neurological findings, school performance and a number of behavioural characteristics except for a marginal excess of hyperactivity and an excess of sleep disturbances in the study group. It is questionable whether the differences represent a direct effect of clonidine on prenatal development but the dose-effect relationship and the fact that the same effects have been found in rats suggest that this may be so.