The potential teratogenic properties of benzodiazepine (BZD) intake during early pregnancy were investigated at the Departments of Pediatrics, Pathology and Genetics at Goteborg University, Sweden. Four neonatal diagnoses of congenital malformations known to be characteristic of infants born to mothers with excessive intake of BZD in early pregnancy were present in 25 of 10,646 live born infants (2.3/1,000) delivered by mothers living in the city of Gothenburg in 1985 and 1986. The maternal plasma was analyzed in 18 of these cases 1.2 to 1.5 years after the birth of the probands; eight samples (44%) were BZD positive. Of 60 controls, two maternal blood samples (3%) were positive for BZD. The difference was highly significant and suggests an association between the congenital malformation and BZD consumed during early gestation. 
COMMENT. The diagnoses considered to be specific for BZD-induced congenital malformations were embryopathy and fetopathy, nervous system malformations, cleft lip and cleft palate, congenital malformations of the urinary tract. The authors considered that their findings strengthened the hypothesis that BZD intake during early pregnancy is associated with teratogenicity in man but there is as yet no firm proof of association. Diazepam in early pregnancy should be avoided on the basis of this and other studies which strongly suggest a teratogenic effect of BZD.