Fetal hydantoin syndrome: Inhibition of placental folic acid transport as a potential mechanism for fetal growth retardation in the rat

Maternal hydantoin ingestion during pregnancy results in a well defined clinical entity termed 'fetal hydantoin syndrome'. The clinical characteristics of this syndrome includes growth retardation, and congenital anomalies. Because folic acid is essential for protein synthesis and growth, and since hydantoin interferes with intestinal transport of folic acid, we postulated that part of the fetal hydantoin syndrome may be due to inhibition of placental folic acid by maternal hydantoin. Therefore, we studied in vivo placental folate transport in a well-established model for fetal hydantoin syndrome in the rat. Our results indicate that maternal hydantoin ingestion, significantly decreased fetal weight and placental and fetal uptake of folate compared to controls. To determine whether maternal hydantoin ingestion has a generalized or specific effect on placental function, we examined placental and fetal zinc transport in the same model. Our results indicate that zinc transport is not altered by hydantoin ingestion. We conclude that maternal hydantoin ingestion results in fetal growth retardation which may be due in part to inhibition of placental folate transport.