| FDA Category |
Definition |
| A |
Controlledstudies in animals and womenhaveshown no risk in thefirsttrimester, and possible fetal harmisremote. |
| B |
Either animal studieshavenotdemonstrated a fetal riskbutthere are no controlledstudies in pregnantwomen, or animal studieshaveshownan adverse effectthatwasnotconfirmed in controlledstudies in women in thefirsttrimester. |
| C |
No controlledstudies in humanshavebeenperformed, and animal studieshaveshown adverse events, orstudies in humans and animalsnotavailable; giveifpotentialbenefitoutweighstherisk. |
| D |
Positive evidence of fetal riskisavailable, butthebenefitsmayoutweightheriskiflife-threateningorseriousdisease. |
| X |
Studies in animalsorhumans show fetal abnormalities; drugcontraindicated |
*Data from Food and Drug Administration. Regulations 1980; 44:37, 434-437, 467 |