Methotrexate and Pregnancy: What Happens If You Conceive

What does the evidence say about methotrexate during pregnancy?

1. MotherToBaby states that the product label recommends avoiding methotrexate in pregnancy unless it is being used for cancer, while recognizing that unusual situations need clinician-specific risk-benefit review. 1
2. In a prospective cohort, post-conception methotrexate exposure was associated with more miscarriages than both comparison groups. Major birth defects were significantly more frequent than in the group without autoimmune disease; the comparison with disease-matched pregnancies was statistically uncertain. Pre-conception exposure did not show these increases. 2
3. A population-based study reported that maternal methotrexate exposure was uncommon and supported concern about an association with congenital heart differences, while stressing the need for larger studies. 3
4. A nationwide study did not find an association between paternal methotrexate exposure shortly before conception and congenital malformations, stillbirth, or preterm birth. 4
5. MotherToBaby notes that most methotrexate has cleared within about a week in healthy non-pregnant adults, but clearance can vary and product-label waiting advice is longer than some clinician recommendations. 1

Is methotrexate safe in each trimester?

• First trimester. First-trimester methotrexate exposure is the key concern because reported patterns of birth differences involve early development. Prompt review can clarify the dose, timing, indication, and pregnancy dating.
• Second trimester. Methotrexate is generally avoided later in pregnancy unless a specialist determines that an exceptional indication changes the balance of risks and benefits.
• Third trimester. In late pregnancy, methotrexate decisions remain specialist-led. Planning also needs to include the underlying autoimmune disease or cancer and the newborn feeding plan.