Distal phalangeal hypoplasia in children with prenatal phenytoin exposure: Results of a controlled anthropometric study

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Abstract
Phalangeal and metacarpal bone length was measured from hand radiographs in 111 children of epileptic mothers and 96 control children of nonepileptic mothers. Seventy‐six children of the study group had been exposed to phenytoin in the first 20 weeks of pregnancy, 21 had been exposed to other antiepileptic drugs excluding phenytoin, and 14 had not been exposed. Distal phalangeal lengths were significantly reduced in phenytoin‐exposed children. The second and fifth digits were most affected. Phenytoin exposure was associated with a significantly elevated prevalence (11%) of radiologically defined distal phalangeal hypoplasia. The subgroup of children exposed to phenytoin levels over 40 μmol/I showed more prominent effects than did the subgroup exposed to lower or unknown concentrations. These results confirm that early fetal exposure to phenytoin decreases distal phalangeal size, as suggested by several previous studies relying on clinical examination only. Distal phalangeal hypoplasia was not accompanied by other serious abnormalities.