Certain Drugs During Pregnancy Dangerous

B O S T O N, Nov. 29, 2000 -- Drugs that interfere with the body’s use of folicacid can increase the risk of a variety of birth defects if takenduring pregnancy, a study found.

Researchers agree that lack of folic acid during pregnancyraises the risk of spina bifida and other neural tube defects.However, the suspected link with some other birth defects is lessclear.

To study this, doctors checked to see if the risk of thesedefects increases if mothers take medicines known to disrupt thebody’s breakdown and absorption of folic acid.

Did Drugs Play Role in Defects? Researchers from Boston University’s Sloan Epidemiology Unitreviewed 6,932 infants born with oral clefts or defects of theheart or urinary tract. They were compared with 8,387 babies withother defects not thought to be caused by lack of folic acid.

Most drugs that can disrupt folic acid are known asdihydrofolate reductase inhibitors. They include the cancer drugsaminopterin and methotrexate; sulfasalazine, an anti-inflammatorydrug; pyrimethamine, used to treat protozoal infections;triamterene, a diuretic; and trimethoprim, an ingredient of theantibiotic Bactrim.

Some drugs used to treat epilepsy, including phenytoin,phenobarbital, primidone and carbamazepine, can also can affectfolic acid.

Some Drugs Did Increase Defects

The researchers found that the risk of heart defects and oralclefts roughly tripled if mothers used dihydrofolate reductaseinhibitors during the first three months of pregnancy. It doubledif they used the epilepsy medicines.

Women of childbearing age are urged to take multivitamins tomake sure they get enough folic acid. The study found that thevitamins reduced much of the extra risk of birth defects amongwomen using the dihydrofolate reductase inhibitors but not amongthose taking the epilepsy medicines.

The study was directed by Dr. Sonia Hernandez-Diaz and publishedin Thursday’s New England Journal of Medicine. It was financed bythe Harvard School of Public Health and several government agenciesand drug companies.