Safety concerns drive call for drug studies that involve pregnant women

Mattison said researchers who are part of an obstetric-fetal pharmacology network are slowly learning more. They have determined, for instance, that the typical dose of a certain diabetes medicine is insufficient to aid pregnant women, who may need four times as much medication. But doctors need to know more before upping the dose because the medication crosses the placenta, and a higher dose could hurt the fetus.

This is how most drug research on pregnant women is done - by studying women who have decided it was safer to stay on their medications during pregnancy. Untreated asthma, for example, can lead to pre-term labor and low birth weight.

Drug companies are also accumulating some information, both through complaints and through pregnancy registries where the health of medicated mothers and their babies are closely monitored.

The FDA is developing labeling rules that would specify what is and is not known about how every drug on the market affects pregnancy

"The realization that a lack of data can cause harm is pulling people together to start a serious conversation about how to best obtain data that is needed," the FDA's Feibus said.

Faden has been trying to start the conversation for more than 15 years, but has found that ethical concerns have outweighed the health concerns for pregnant women and their unborn children.

"We are so conflicted as a nation on how to think about what we owe to very early life," she said. "Nobody wants to touch it."

That, she thinks, could be changing.

"There is a growing consensus that the current situation is unfair," she said. "We need to push as far as we can."