Methotrexate During Pregnancy and Breastfeeding

by on May 12, 2012

Women who may have been or are currently being treated for psoriasis, rheumatoid arthritis, lupus, Crohn’s Disease, or various forms of cancer have possibly taken methotrexate as part of their treatment regimen. Before becoming pregnant, women with a history of methotrexate treatment, or who are currently taking it, need to evaluate the risks and warnings of this powerful drug.

Prolonged use of methotrexate will cause the body to build up levels of the drug in body tissues, specifically in the liver and gall bladder, spleen, and kidneys.  If a woman stops taking methotrexate and wishes to become pregnant, she should wait at least 6 months before conception. It is not proven that residual methotrexate in a pregnant woman’s body will effect the development of a fetus, but waiting for 6 months will reduce the level of risk.

Folic Acid

Folic acid is a B-vitamin which is important for healthy cell growth. Everyone needs folic acid in their diet, but women who are pregnant need extra folic acid in their diets, or as a supplement, to insure the fetus develops normally. Methotrexate is an antifolate drug. This term means that methotrexate interferes with the body’s metabolism of folic acid.

During the first trimester development and growth of the fetal spinal cord, brain, heart, arms, legs, eyes and ears progresses rapidly. At 7 weeks gestation, all essential organs are present. Methotrexate can interfere with this development causing devastating results.

Category X

The FDA categorizes drugs according to their potential risks. The Pregnancy Category List contains 5 categories ranging from A through D and X. A is the category having no risk and X is the category that is known to cause birth defects.  Methotrexate is rated as a Category X drug because it has teratogenic effects. This means that it is known to cause deformities or abnormalities in developing fetuses. Category X is not rating a level of risk. Category X means that the drug should not to be taken during pregnancy because it does cause birth defects.

Methotrexate Uses in Pregnancy

Not only is methotrexate used to treat autoimmune disorders and cancer, it is also prescribed for ectopic pregnancies. If a fertilized egg attaches outside the womb, such as inside the Fallopian tube, or on the abdominal wall, it cannot survive and may cause bleeding and other complications. Methotrexate will effectively decrease the pregnancy hormone levels and end the pregnancy. Ending ectopic pregnancies as well as normal in utero pregnancies can be accomplished with high doses of methotrexate.

Methotrexate and Breastfeeding

Just as methotrexate passes through the placenta to the developing fetus, it also is present in breast milk and will be passed on to the nursing infant.

Women who are nursing should not take methotrexate for this reason. Introducing a drug that causes disruption in cell division to a newborn infant even in breast milk, should be avoided. Studies have not proven links between methotrexate in breast milk to development issues in infants, but since the effects of methotrexate are known to be toxic, the best choice would be to avoid it.

Methotrexate is a cytotoxic drug that has been shown to cause birth defects. It can induce spontaneous abortions and should never be taken during pregnancy.