Congenital malformations and maternal consumption of benzodiazepines: a case-control study

This study assessed potential teratogenic properties of benzodiazepine (BZD) intake during early pregnancy. Four neonatal diagnoses of congenital malformations (embryopathy and fetopathy, unspecified; unspecified congenital malformations of the nervous system; cleft palate and cleft lip; congenital malformations of the urinary tract) were selected. The authors' previous clinical experience had shown these diagnoses to be characteristic of infants born to mothers with excessive intake of BZD in early pregnancy. The selected diagnoses were present in 25 of 10,646 liveborn infants (2.3 per 1000) delivered by mothers living in the city of Gothenburg in 1985 and 1986. In 18 of these cases, it was possible to analyse maternal plasma, and eight samples (44 per cent) were found to be BZD-positive. Of 60 controls, two maternal blood samples (3 per cent) were positive for BZD. The difference is highly significant and suggests an association between these congenital malformations and BZD consumed during early gestation.