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In animal studies on tamoxifen and pregnancy, the drug was shown to not only increase the risk of miscarriages, but also to increase the risk of vaginal or cervical cancer later in life. As a result, the FDA has classified the drug as a pregnancy Category D medication. If you are taking tamoxifen and pregnancy occurs, your healthcare provider will weigh the benefits and risks before making a recommendation.

Tamoxifen and Pregnancy: An Overview

Tamoxifen citrate (Nolvadex®, Soltamox™) is generally not considered safe for women who are pregnant. In animal studies that looked at the effects of the drug during pregnancy, it was shown to cause miscarriages and problems for the animals later in life.

Tamoxifen and Pregnancy Category D

The U.S. Food and Drug Administration (FDA) uses a category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Pregnancy Category D is given to medicines that have shown clear evidence of risk to the fetus in studies. This is a stronger warning than a pregnancy Category C classification. However, a pregnancy Category D medicine may still be given to a pregnant woman if the healthcare provider believes that the benefits to the mother outweigh the possible risks to the unborn child.
Tamoxifen was given a pregnancy Category D rating because of problems in animal studies. When given to pregnant rats, the drug increased the risk of miscarriage. In addition, there is evidence that female rodents that were exposed to tamoxifen as fetuses have a higher risk of vaginal or cervical cancer.
The manufacturers of tamoxifen recommend that women should not become pregnant while taking the drug or within two months of taking it. Women who may become pregnant should use non-hormonal contraception (such as condoms) while taking the drug and for at least two months after taking it.
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Last reviewed by: Kristi Monson, PharmD;
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