fetal hydantoin syndrome (FHS), a complex of birth defects associated with prenatal maternal ingestion of hydantoin derivatives. Symptoms of FHS include microcephaly, hypoplasia or absence of nails on the fingers or toes, abnormal facies, mental and physical impairment, and cardiac defects. The syndrome occurs to some degree in 10% to 40% of infants born of mothers who use this anticonvulsant. Hydantoin is sometimes associated with hemorrhage and, more rarely, with neural crest tumors in the newborn.
