Disease activity of rheumatoid arthritis during pregnancy: results from a nationwide prospective study

According to common knowledge and retrospective studies, approximately 75-90% of patients with rheumatoid arthritis (RA) will improve during pregnancy. Prospective data on disease activity during pregnancy are limited. Therefore, this study aimed to prospectively determine the disease activity during pregnancy in RA patients treated in an era of new treatment options.

For 84 RA patients (American College of Rheumatology criteria), a Disease Activity Score in 28 joints (DAS28) and medication use were obtained, before conception if possible, at each trimester of pregnancy and at 6, 12, and 26 weeks postpartum. Improvement and deterioration were determined by assessing changes in DAS28 and by applying the DAS28-derived European League Against Rheumatism (EULAR) response criteria.

Disease activity decreased with statistical significance (P = 0.035) during pregnancy and increased postpartum. In patients with at least moderate disease activity in the first trimester (n = 52), at least 48% had a moderate response during pregnancy according to EULAR-defined response criteria. In patients with low disease activity in the first trimester (n = 32), disease activity was stable during pregnancy. Thirty-nine percent of patients had at least a moderate flare postpartum according to reversed EULAR response criteria. Less medication was used during pregnancy compared with before conception and compared with postpartum.

This study demonstrates that patients achieve remission during pregnancy and deteriorate postpartum, although less frequently than previously described.