Women often take medications before they realize they are pregnant, which creates an opportunity for researchers to study the drug's effects on the baby. (CBC)

Medications are rarely tested for safety in pregnant women, but proposed federal guidelines could discourage studies that might offer better information and help ease the worries of expectant mothers, some researchers and ethicists say.

The proposed guidelines apply to human research by scientists, universities and hospitals receiving federal funding.

The draft guidelines prohibit the inappropriate exclusion of pregnant women from research, said Susan Zimmerman, executive director of the secretariat on research ethics, which supports the work of the panel adopting the guidelines.

But there is dispute on how these draft guidelines will be interpreted and applied by researchers. Some say pregnant women will still be left out.

Many of the 400,000 women who become pregnant in Canada every year worry about safety when deciding to take drugs they may need. Some deny themselves treatment for fear of harming the fetus, given that most medication labels clearly say not to take during pregnancy or there is not enough data to show safety in pregnancy.

Krista Carter of Truro, N.S., has to take medication for a severe anxiety disorder. She took anti-anxiety medication during her first two pregnancies, and worried about the effect it would have on her babies. They were fine, but she is about six months into her third pregnancy and still worrying about potential side-effects on the baby.

"You're supposed to be happy during the whole nine months, not anxious, wondering what's going to happen, if they're going to be OK when they're born," said Carter, adding there has been no research to ease her concerns.

Dilemma for researchers

It is also a dilemma for researchers, said Françoise Baylis, Canada Research Chair in bioethics and philosophy at Dalhousie University in Halifax.

"I think there are researchers who'd like to do research in this area and they don't have confidence that a research ethics board will approve it," said Baylis. "They have pharmaceutical companies telling them stories about liability and they don't want to go near it."

'If you don't have a framework or infrastructure that says it's legitimate to do this [research], but under these kinds of constraints which provide appropriate protections, then it just won't happen.'— Françoise Baylis

There are ways to safely study the effects of drugs in pregnant women. About half of pregnancies in North America are unplanned, and often women have taken medications before they realize they are pregnant, said Dr. Gideon Koren of the Hospital for Sick Children in Toronto.

Koren runs the Motherisk program at Sick Kids, which collects information from about 200 such cases each day. Researchers then track what happened to babies after their mothers continued to take medication during the pregnancy.

The U.S. Food and Drug Administration now requires drug manufacturers to collect such data in registries, including for drugs that do not state on the label that the drug is safe for use in pregnancy. But Canada is not doing that, Koren said.

"If an ethicists' forum [said] loud and clear that it's unethical not to collect such data because it's the only way we can do it when women are exposed, I think it will send a very clear message to the scientific community, to the manufacturing community, that it must be done," Koren said.

The FDA has launched a major study to review the medical records of about one million women and their children to see what the impact was on babies whose mother took prescription drugs during pregnancy.

Koren and other researchers are upset that a proposed ethical rule doesn't specifically state that pregnant women should not be excluded from research solely on the basis of pregnancy.

Pregnant women missing out

Without this rule, scientists will continue to leave pregnant women out of studies, Baylis and Koren said. Studies by pharmaceutical companies testing a new drug typically require women to take contraceptives to avoid pregnancy.

The lack of a rule means women who are expecting will continue to be forced to make health choices based on case studies rather than higher quality research information, Baylis added.

"If you don't have a framework or infrastructure that says it's legitimate to do this, but under these kinds of constraints which provide appropriate protections, then it just won't happen," Baylis said.

Without the research, many medications developed in the last 50 years don't get prescribed to pregnant women, Koren noted.

Researchers can also ask women who are planning to terminate a pregnancy to take a medication to see what effect it has on the fetus. Internationally, there have been 60 such studies, Koren said.

Another way to gain valuable information is to study the babies of women with chronic conditions who need medication while pregnant, such as Carter. If a researcher asked her to be part of such a study, Carter said she would absolutely participate because it might help someone else.

The federal panel creating the research guidelines is inviting public comment until March 1.

"The guidelines place a positive obligation on researchers to be inclusive in defining who to include in their research, based on the scope and objectives of the research," Zimmerman said in an email.

"This means that research on interventions intended for pregnant women, or which may be used on pregnant women, should include pregnant women."

The public review aims to identify and address gaps in the existing research ethics guidelines and improve their clarity.

The final draft will be prepared in April, and then submitted to Canada's three research councils for approval.