It is also the area in which there is the least amount of hard scientific data about what's safe and what isn't. Drugs are almost never tested on pregnant women. Advances in medicine have enabled us to treat diseases, but that has resulted in pregnant women being exposed to medicines more than ever before.
Some medicines are life saving, others are less critical.
There are many large reference books devoted to this topic and each drug comes with a package insert that includes information about whether the medicine is considered safe in pregnancy. Below are a few examples of the safety of certain medications in pregnancy. In future columns I will address specific groups of drugs. With a few exceptions, most antibiotics are safe in pregnancy. Erythromycin is often used for things like ear infections because it crosses the placenta least.