The use of medications during pregnancy is always difficult due to the potential risks a medication may pose to the growing fetus. Pregnancy categories are used to define the safety of a medication during pregnancy but it is important to note a medication may have different categories during different trimesters.
A-Adequate, well-controlled studies have shown the medication is safe for use in the first trimester of pregnancy and has not show problems in later trimesters. This means that the medication has not shown evidence to be of damage to the fetus.
B- Animal studies have not show a risk to the fetus but there is not enough information in human studies or there were adverse effects in animal studies but there were no adverse effects seen in well-controlled human studies
C- Indicates there is not enough information in human and animal studies or there were adverse effects in animal studies but there is no enough human data available. Potential benefits of the drug may warrant its use in pregnant women.
D-There is evidence of fetal risk in both human and animal studies but if the benefits out-weigh the risks, the medication may be considered.
X-There is evidence of fetal risk in both human and animal studies. These drugs should not be considered for use in any pregnant female.