In Canada, 50 percent of pregnant women take prescription medication. Yet many of them prefer to use natural health products during the pregnancy. "We believe these products to be safe because they are natural. But in reality, they are chemical products and we don't know many of the risks and benefits of these products contrarily to medication," says Bérard.

Bérard and Moussally set out to conduct one of the largest studies ever undertaken on by analyzing data from 3354 Quebec women. The first part of the research established that close to 10 percent of women between 1998 and 2003 used natural health products during their pregnancy. Before and after pregnancy they were respectively 15 and 14 percent to use these products. The increase means that about a third of women consuming natural health products stopped during the pregnancy.

The most consumed natural health products by pregnant women are chamomile (19 percent), green tea (17 percent), peppered mint (12 percent), and flaxseed oil (12 percent). Bérard and Moussally correlated these products to premature births and only one product had a very strong correlation: flaxseed oil.

"In the general population, the average rate of premature births is 2 to 3 percent. But for women consuming flaxseed oil in their last two trimesters that number jumps up to 12 percent," says Bérard. "It's an enormous risk."

The correlation existed only with flaxseed oil, yet women consuming the actual seed were unaffected. Even if more studies must be undertaken to verify these results, Bérard recommends caution when it comes to consuming flaxseed oil.

Note: If no author is given, the source is cited instead.

• Menopause
• Pregnancy and Childbirth
• Gynecology

• Food
• Mating and Breeding
• Biochemistry Research

• Fertility
• Oily fish
• Nutrition and pregnancy
• Food groups
• Miscarriage
• Premature birth