Dilantin, also called phenytoin, is a medication taken by some people for control of seizures. Like all anti-seizure medications, Dilantin can cause problems for the fetus when used by a woman during pregnancy, especially during the first three months. Although most babies exposed prenatally to Dilantin are healthy, it's estimated that about 10 percent have some type of adverse outcome.
Physical Abnormalities
Babies exposed to Dilantin during pregnancy can show a number of different abnormalities, especially heart defects and facial clefts. Approximately 10 percent of Dilantin-exposed babies develop the fetal hydantoin syndrome, which is characterized by dysmorphic facies (short nose, low nasal bridge, epicanthic folds, hypertelorism, abnormal ears, wide mouth), underdevelopment of the ends of the fingers, fingerlike thumbs, short or webbed neck, low hairline, slow growth and abnormal mental and/or motor development. Overall, prenatal exposure to Dilantin has been found to result in a twofold to threefold increased risk for a congenital anomaly, compared to the general population risk. It's thought that part of the increased risk may be attributable to the maternal epilepsy itself, and not to the medication.
Neurological Problems
Prenatal dilantin exposure is known to be associated with lowered intelligence. For example, a study by Scolnik et al (1994) found that children exposed to Dilantin prenatally had mean IQ scores 10 points lower than children not exposed to Dilantin, and lower scores on a language development test as well. Dilantin exposure has also been suggested to delay locomotor development, such as crawling and walking.
Other Problems
In a study by Arulmozhi et al (2006), babies exposed prenatally to Dilantin had significantly lower birth weights than controls not exposed to Dilantin. In addition, the study noted delays in the lengths, head circumference, and ability to sit alone in the babies exposed to Dilantin as compared to the controls. Dilantin use during pregnancy may also increase the risk of tumors, including ependymoma, neuroblastoma and Wilms' tumor.
About half of babies exposed to Dilantin prenatally are deficient in vitamin K-dependent clotting factors and therefore develop a bleeding disorder. It's possible that some of the developmental abnormalities associated with Dilantin exposure may be caused in part by this vitamin K deficiency. Vitamin K-associated bleeding problems can be prevented by injecting a vitamin K supplement at birth.
Benefits of Dilantin therapy must be weighted against the risks. If a mother experiences seizures during her pregnancy, this is thought to be more risky for the fetus than the mother's use of an anti-seizure medication.
References
- American Journal of Medical Genetics; Teratogen-Induced Limb Defects; LB Holmes; 2002
- Journal of the American Medical Association; Neurodevelopment of Children Exposed in Utero to Phenytoin and Carbamazepine Monotherapy; D Scolnik et al.; 1994
- Neurology India; Physical Growth and Psychomotor Development of Infants Exposed to Antiepileptic Drugs in Utero; T Arulmozhi et al.; 2006
