About two-thirds of pregnant women are prescribed medications during pregnancy that are not their vitamins. If you want to know what you are taking is safe, read the label, but it's probably confusing. And the language it's written in and the research it's based on may be as confusing to your gyno as to you! And when you ask questions, the most important question to start with: what is your background risk of having a complication?
Some conditions in pregnancy always get treated with medication. Nausea and vomiting in pregnancy probably occurs in about 85% of all women who are pregnant. We once had a drug in the US called Bendectin, and in 1983 it was removed from the US market. It was a combination of doxylamine and Vitamin B6. That very combination is still sold in Canada.without any undue reports of abnormalities.
In the USA we have a sleep medicine called Unisom, and it's actually doxylamine, so we can cobble together the old combination to use if we want to. And it's a good one. But we've switched to using ondansetron. The use of this medicine grew rapidly because it was so effective, long before any safety studies were published. Then the safety studies were "look back," or what are called retrospective studies, and they were often big! As many as 5000 women - and the good news was that the look back studies showed that there were no reasons for the physicians to feel that this drug was not safe.
There are lots of ways to track the safety of the medications that you are taking when you are pregnant. It's important to know if there are new alerts or new studies, so keep vigilant in watching the news and talking with your health care provider. Your physician might be using PubMed or the Web of Science to find answers to questions regarding exposures and risks.