Shmerling, who was not involved in the new research, points out, however, that “this single study is unlikely to be the last word on the matter,” given its small size, the lack of information about methotrexate dose (higher doses could come with more risk), and the lack of confirmation that the men actually took methotrexate, only that they filled prescriptions for it.
He also notes that, because information on pregnancy termination and miscarriage was not available, if methotrexate caused fetal malformations that led to these events, the study would have missed them.
“Therefore, it may be premature to conclude with confidence that methotrexate taken by men has no impact on fetal health if their partners become pregnant,” Shmerling says. “However, guidelines could and should acknowledge the reassuring data to date and the remaining uncertainties.”
- Eck LK, Jensen TB, Mastrogiannis D, et al. Risk of adverse pregnancy outcome after paternal exposure to methotrexate within 90 days before pregnancy. Obstet Gynecol. 2017 Mar 6. doi: 10.1097/AOG.0000000000001936. [Epub ahead of print]