FDA Use in Pregnancy Ratings [1,2,3]
The Food and Drug
Administration (FDA) created the rating system below to simplify the
risk-benefit information for a given drug.
this system oversimplifies the issues important to prescribing a medication to a
"The letters imply a gradation of risk that doesn't necessarily exist, says
the FDA's Kweder. People falsely assume that drugs labeled as category X pose
the most risk in pregnancy and drugs labeled as A pose the least. But X reflects
a benefit-risk judgment, and drugs in that category may be no more toxic than
drugs called C or D... Some drugs, such as oral contraceptives, land in Category X simply because
there is no reason to use them in pregnancy" 
The U.S. Food and
Drug Administration (FDA) has recommended the elimination of the current
pregnancy categories A, B, C, D, and X. In place of the current system the FDA has proposed that the
pregnancy and lactation subsections of labeling should include a summary, which
summarizes the risks of the medicine to the developing baby (fetus) or
breast-feeding infant, and a discussion of the data supporting that summary 
Adequate, well-controlled studies in pregnant women have not shown an increased risk
of fetal abnormalities to the fetus in any trimester of pregnancy.|
Animal studies have revealed no evidence of harm to the fetus, however,
there are no adequate and well-controlled studies in pregnant women.|
Animal studies have shown an adverse effect, but adequate and
well-controlled studies in pregnant women have failed to demonstrate a risk to
the fetus in any trimester.
Animal studies have shown an adverse effect and there are no adequate
and well-controlled studies in pregnant women.|
No animal studies have been conducted and there are no adequate and
well-controlled studies in pregnant women.
Adequate well-controlled or observational studies in pregnant women
have demonstrated a risk to the fetus.
However, the benefits of therapy may
outweigh the potential risk. For example, the drug
may be acceptable if needed in a life-threatening situation or serious disease
for which safer drugs cannot be used or are ineffective.
Adequate well-controlled or
observational studies in animals or pregnant women have demonstrated positive
evidence of fetal abnormalities or risks.
The use of the product is contraindicated in women who are
or may become pregnant.
Created: 11/11/2012 Mark A Curran, M.D.
Physician's Desk Reference 57th ed. Montvale, NJ: Thomson PDR;
2. Meadows M.. Pregnancy and the drug dilemma. FDA Consum. 2001
3. Briggs GG,Freeman RK, Yaffe SJ, Drugs in Pregnancy and Lactation 6th edition,Baltimore, MD:
Williams & Wilkins,2002.
Pregnancy & Lactation Labeling. U.S. Department of Health & Human Services
12/18/2009 .Accesssed 1/27/09