A wide range of drugs used for treating epilepsy, mood disorders, hypertension and infections are folic acid antagonists. This means that they interfere with the action of folic acid and produce the symptoms of a folic acid deficiency.

Exposure to folic acid antagonists in pregnancy has been associated with a higher risk of suffering placenta-mediated adverse reactions such as preeclampsia, placental abruption, fetal growth restriction or fetal death.

Since about 50% of pregnancies in industrialized countries are unplanned, there is an increased unintended exposure to such medications.

The researchers from Ottawa, Montreal, Saskatoon and Hunan, China looked at 14 982 women who had taken folic acid antagonists one year prior to delivery and 59 825 women who did not. They found that maternal exposure to folic acid antagonists was associated with a slightly higher risk of adverse pregnancy outcomes.

As a result of the study findings, the researchers suggested re-classification of some folic acid antagonists and recommended increased folic acid supplements for women taking folic acid antagonists during their pregnancies.