Use of antirheumatic drugs in mothers and fathers before and during pregnancy-a population-based cohort study.

Purpose: Exploring the use of antirheumatic drugs in pregnant women and expectant fathers.

Methods: Population-based cohort study, based on linkage of two nationwide databases: the Norwegian Prescription Database was linked to data on 106 000 pregnancies during 2004-2006 from the Medical Birth Registry of Norway. Antirheumatic drugs dispensed to mothers 3 months prior to conception, during pregnancy, and up to 6 months after delivery, and prescriptions to fathers 3 months prior to conception were identified.

Results: During the 18-month observation period for each pregnancy, 1411 women (1.3% of the women) redeemed at least one antirheumatic drug. Of these, 45% received at least one drug during 3 months prior to conception and 28% in the first trimester. Four women redeemed prescriptions for methotrexate during the 3 months prior to conception, and two women did so during the pregnancy. One of the four women on leflunomide, received the drug 3 months before conception, and two of them during the first trimester. Among the women using etanercept, 19 women redeemed the prescription 3 months before pregnancy, 11 during the first trimester, one in both the second and third trimesters. Three months prior to conception, 837 expecting fathers (0.8%) redeemed at least one prescription: 40 had sulfasalazin, 36 methotrexate and 28 had biological drugs.

Conclusion: Three women redeemed leflunomide or methotrexate, which have known teratogenic effects, during their first trimester. While there are high levels of awareness about maternal drug use in pregnancy, drug exposure in fathers shortly before conception should be further explored.