Folic acid supplements don’t prevent pre-eclampsia, Canadian study shows

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 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 second-leading 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.

The 2011-2016 study recruited about 2,300 pregnant women at risk for preeclampsia, who were enrolled at 70 centres in five countries – Canada, the U.K., Australia, Jamaica and Argentina.

Half the women were randomly assigned to take four extra milligrams of folic acid daily, while the other half received a placebo pill.

“(What) we found was there was absolutely no difference between the group treated with high-dose folic acid and the placebo,” Walker said.