Can I take methotrexate while pregnant or breastfeeding?

8.1 Pregnancy Risk Summary Methotrexate tablets are contraindicated in pregnant women with non-neoplastic diseases [see Contraindications ( 4 )] . Based on published reports and its mechanism of action [see Clinical Pharmacology ( 12.1 )] , methotrexate can cause embryo-fetal toxicity and fetal death when administered to a pregnant woman. There are no animal data that meet current standards for nonclinical developmental toxicity studies. Advise pregnant women with neoplastic diseases of the potential risk to a fetus. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

Prescribing label, section “8.1 Pregnancy” (opening excerpt): Methotrexate (oral), A-S Medication Solutions. Read the full section on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.

Maternal doses of methotrexate up to 92 mg (1.12 mg/kg) produce low levels in milk. Pharmacokinetic modeling predicts infant exposure to be less than 1% of the mothers with weekly doses of 25 mg or less.[1] Recent guidelines state that low single or weekly doses, such as those used for ectopic pregnancy or rheumatoid arthritis (25 mg per week or less), are an acceptable alternative during breastfeeding,[2,3] although some older expert opinion warns against this use.[4,5] Withholding breastfeeding for 24 hours after a weekly low dose of methotrexate may decrease the infant's dose by 40%.[6-8] If breastfeeding during long-term, low-dose methotrexate use is undertaken, monitoring of the infant's complete blood count and differential and liver enzymes can be considered.

Most sources consider breastfeeding to be contraindicated during maternal high-dose antineoplastic drug therapy with methotrexate. An abstinence period of at least 1 week after chemotherapy doses of methotrexate has been suggested.[9] Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk.[10] Women who receive chemotherapy during pregnancy are more likely to have difficulty nursing their infant.[11]

“Summary of Use during Lactation”, LactMed record “Methotrexate” (LM466), quoted verbatim. Everything LactMed reports about Methotrexate while breastfeeding.

8.2 Lactation Risk Summary Limited published literature report the presence of methotrexate in human milk in low amounts, with the highest breast milk to plasma concentration ratio reported to be 0.08:1. There are no data on the effects of methotrexate or its metabolites on the breastfed child or their effects on milk production. Because of the potential for serious adverse reactions in a breastfed child, instruct women not to breastfeed during treatment with methotrexate tablets and for 1 week after the final dose.

Prescribing label, section “8.2 Lactation”: Methotrexate (oral), A-S Medication Solutions. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.