Antenatal exposure to meprobamate and chlordiazepoxide in relation to malformations, mental development, and childhood mortality.

In a follow-up study of 50,282 pregnancies (lasting at least five lunar months) and the offspring, malformations identified before the first birthday, or at death before the fourth birthday, were identified in 3248 children (6.5 per cent). A total of 1870 children exposed in utero to meprobamate or chlordiazepoxide were compared with 48,412 children who were not. No significant differences were found either overall or in specific outcomes; rates were also similar when exposures occurred during the first trimester or at other times during pregnancy. Deaths (stillbirth to the fourth birthday) occurred in 2227 children (4.4 per cent), and there was no evidence that antenatal exposure to either drug increased the death rate. Finally, as judged by mental and motor scores at the age of eight months, and intelligence quotient scores at four years, there was no evidence that the drugs cause brain damage.