Folic acid doesn’t prevent pre-eclampsia, study finds

TORONTO Taking high-dose folic acid during pregnancy does not prevent pre-eclampsia in women at elevated risk for the potentially deadly condition, a Canadian-led international study has found.

The finding, which refutes a long-held belief about folic acid’s preventive role in pre-eclampsia, is expected to alter the practice of prescribing extra doses of the B vitamin to high-risk pregnant women worldwide.

Principal investigator Dr. Mark Walker of the University of Ottawa said the study's finding doesn’t mean foregoing low-dose folic acid, which is taken to prevent fetal neural-tube defects, which can cause such conditions as spina bifida.

“All women should take folic acid for at least three months prior to conception,” said Walker, chief of obstetrics and gynecology at the Ottawa Hospital. “I think it’s safe and efficacious to take .4 to 1 milligram of folic acid in a multivitamin throughout the pregnancy.

“However, those women who are at risk for pre-eclampsia, there is no benefit to being on a high dose of folic acid.”

Pre-eclampsia is a condition caused by elevated blood pressure as a result of pregnancy. It is the secondleading cause of maternal death in Canada after venous blood clots that go to the lungs. Each year, about 78,000 women around the world die from the condition.

After pre-term birth, pre-eclampsia is also the second-leading cause of perinatal mortality in Canada, “so it’s a big contributor to still birth as well as neonatal death,” said Walker.

Walker said previous observational studies, by his team and other research groups around the globe, had led to the conclusion that having high-risk women take an extra four mg of folic acid daily during pregnancy would cut the incidence of pre-eclampsia by about 30 per cent.

But the Ottawa scientists wanted to put that notion to the acid test with a large randomized controlled trial, the type of study considered the gold standard of medical research.