First trimester exposure to certain medications such as folic acid antagonists is associated with increased risk for neural tube, cardiovascular and urinary tract defect.

For pregnant women, folic acid is the most important supplement during the first few weeks of gestation and beyond. For optimal fetal development, folic acid should be started before conception occurs, but since only low levels or no levels are included in daily vitamins, early pregnancy detection can be the fetuses saving grace. New research has found that folic acid absorption, no matter the level of supplementation, may be thwarted by certain prescription medications.

Data was collected from 84,832 babies born at the Soroka University Medical Center in Israel. "After studying the data, we concluded that first trimester exposure to folic acid antagonists is associated with increased risk for neural tube, cardiovascular and urinary tract defects," says Dr. Rafael Gorodischer. Gorodischer was the principal investigator in the study.

During the study, researchers investigated the effect of two types of medications on the folic acid levels in the pregnant female. The dihydrofolate reductase inhibitors stops the conversion of folic acid into a usable form. Common dihydrofolate reductase inhibitors include certain antibiotics, ulcerative colitis medications and certain chemotherapy drugs. The remaining medications are known to decrease the serum levels of folic acid in the blood. These include antiepileptic medications and certain cholesterol reducing drugs.

The researchers found that these medications had the potential to decrease folic acid levels enough to more than double the risk of neural tube development of the fetus during the first trimester.

According to the National Institutes of Health in the United States, the following medications or lifestyle choices may have an effect on folic acid absorption:

  • Alcohol Consumption
  • Aminosalicyclic Acid
  • Antacids
  • Antibiotics
  • Aspirin
  • Birth Control
  • Carbamazepine
  • Chloramphenicol
  • Cholestyramine
  • Colestipol
  • Cycloserine
  • Diuretics
  • Estrogens
  • Methotrexate
  • Methylprednisolone Sodium Succinate
  • Cigarette Smoking
  • Pentamidine
  • Phenobarbita
  • Primidone
  • Pyrimethamine
  • Sulfasalazine
  • Triamterene

Many of these medications are sold under brand names as opposed to their given official drug name.

Source: British Journal of Clinical Pharmacology - October 2009