As soon as Rebecca Oliver knew she was pregnant, she stopped taking three prescription drugs she relies on to control her asthma and bronchitis.
Doctors could not assure her that the drugs were safe for her and her baby.
"The one thing I want -- and I would assume other pregnant women want as well -- you want to be reassured," she said.
But for the thousands of drugs that pregnant women may take, there is inadequate information on the risks.
"Every time you prescribe a drug in one way or another it's an experiment," said Dr. Jason Umans.
Why the lack of information?
The U.S. Food and Drug Administration says pharmaceutical companies have not tested drugs on pregnant women for ethical reasons, and especially because they're afraid of being sued if the fetus is harmed.
But, as a result, doctors currently base their prescriptions on little more than trial and error. There have been report of birth defects caused by the acne drug Accutane, and fetal withdrawal caused by antidepressants.
Umans said these risks are unacceptable.
"I think these women have been denied ... effective therapy that we offer to everyone else," he said.
He is now conducting one of the first government-funded studies on drugs in pregnant women. He chose to study glyburide, a drug commonly used by pregnant women who develop diabetes.
"There is a lot we don't know," he said.
The study will hopefully help doctors determine the safest and most effective doses.
"I did it to help other women who are pregnant," said study participant Laura Hernandez.
The government also is funding research on the use of drugs for pre-term labor, epilepsy and depression in pregnant women.