Women planning pregnancy should boost their intake of folic acid even more, as it could play a key role in reducing as many as half of certain birth defects, according to new guidelines released Wednesday.

The recommendations were produced for health-care professionals by a multidisciplinary panel of experts from the Society of Obstetricians and Gynaecologists of Canada and Toronto's Hospital for Sick Children.

New evidence suggests birth abnormalities, such as congenital heart disease and some early pediatric cancers, can be prevented through folic acid supplementation.
(CBC)

Women with no personal health risks, a planned pregnancy and a diet of foods rich in folate should take a multivitamin containing between 0.4 and one milligram of folic acid at least two to three months before conception and throughout pregnancy, the recommendations say.

However, women who are at higher risk, including those who are smokers, obese, diabetic or with previous history of spina bifida in the family should be supplementing their diet with multivitamins containing five milligrams of folic acid, three months prior to and up to 12 weeks following conception.

After the first 12 weeks, in both at-risk and normal pregnancies, women should take a multivitamin containing between 0.4 and one mg of folic acid, and keep taking it as long as breastfeeding continues.

In the past, recommendations had been made to take folic acid to stem neural birth defects such as spina bifida. However, based on new evidence and research revealing the potential to reduce the occurrence of other birth abnormalities such as congenital heart disease and some early pediatric cancers, the guidelines are now calling for women to step up the level of folic acid supplementation.

"This is the first time that a professional body says give more, more specifically, give five milligrams of folic acid, because if you give only one milligram, quite a few women will not get enough," said Dr. Gideon Koren, director of the Motherisk program at Sick Kids and a senior scientist with the Sick Kids Research Institute.

"That's kind of the summary of the new research that's emerged in the past seven to 10 years."

Koren said folic acid is critical in cell division, which makes it important in the development of the fetus, especially during the first three months, when the organs are produced.

"It's now known since the 1960s that women who gave birth to children with spina bifida appear to have eaten less folic acid than the general population, but it's only through the 1990s using randomized trials using placebos and folic acid show that this is really the case."

Koren said in the last five to 10 years there's been evidence that "other malformations, not just spina bifida, but also malformation of the heart, of the limbs, of the cleft lip, cleft palate, are also preventable by better using folic acid and prenatal vitamins.

"I think the research and evidence that's striking is … there's literally been a reduction in two of the incidences of neural tube defects since this was first introduced, I would say, 15-16 years ago."

Supplement must be taken early: Koren

Since the organs are all formed during the first trimester, the timing of folic acid intake is particularly critical, Koren said.

"If the woman has missed more than that two or three months into her pregnancy, unfortunately, the neural tube is finished. It's fused by four weeks of pregnancy, after one month, so it's too late," he said, adding that the same holds true for other malformations.

While a diet rich in foods fortified with folic acid is also key, supplementation is still needed to achieve the desired level, said Dr. Vyta Senikis, of the Society of Obstetricians and Gynaecologists of Canada.

"If you take a look at good sources of folic acid, what you're looking at are the fortified grains, things like spinach, lentils, chick peas, asparagus, broccoli, corn."

The guidelines also call on Ottawa to consider increasing the fortification of flour with folic acid to 300 mg per 100 g, up from 140 mg, as well as additional fortification for multivitamins.

Folic acid fortification has been mandatory in white flour, enriched pasta and cornmeal in Canada since 1998. 

A spokeswoman for the Public Health Agency of Canada said Wednesday that it had not been formally approached about increasing the level of folic acid fortification.