During pregnancy, when it comes to various health conditions, some medications would be considered safe, some would be considered unknown, and some would be recommended to be completely avoided. The Food and Drug Administration places medications into categories A, B, C, or D based upon their safety levels.
For instance, Claritin is a category B drug, which means that animal studies have shown no known risks to their fetuses, but there are no human studies. Benadryl is also considered to be safe. However, especially during the first trimester, women are often encouraged to take medications with extreme moderation and weight the benefits against any possible risks. Medicines in category A would be considered the safest, but there are few medicines in this category. On the other hand, Ibuprofen (sold under brand names such as Advil and Motrin) is a category D drug and considered to be unsafe during pregnancy, especially during the third trimester. However, it should certainly be avoided all throughout pregnancy or even when trying to conceive.