THU0700 Perinatal exposure to disease modifying antirheumatic drugs in women with inflammatory arthritis and the risk of small-for-gestational-age newborns: a population-based cohort study

Background Currently there exists limited data on pregnancy outcomes among women with inflammatory arthritis (IA) using conventional synthetic DMARDs (csDMARDs), and the risk of small-for-gestational-age (SGA) births. Objectives To investigate the association between csDMARD use before and during pregnancy and SGA births. Methods We linked population-based health data in British Columbia, Canada over a 10 year study period (01/01/2002 – 12/31/2012) on all physician visits, hospital admissions, and dispensed medications with a perinatal registry containing valid information on date of conception. We created a pregnancy cohort of women with IA using a case definition of 2 outpatient physician ICD9 codes≥2 months and ≤2 years apart for rheumatoid arthritis, systemic autoimmune rheumatic diseases, ankylosing spondylitis, juvenile idiopathic arthritis, and psoriatic arthritis. We categorised csDMARDs according to accepted safety profiles - antimalarials, cyclosporine-A, gold, and sulfasalazine (Group 1); and methotrexate, leflunomide, azathioprine, cyclophosphamide, chlorambucil, penicillamine, mycophenolate mofetil, and minocycline (Group 2). We determined exposure as binary use (yes/no) during the 90 days preconception; and during pregnancy from date of conception until date of delivery. The SGA outcome was defined as <10 th percentile of sex- and gestational-age specific weights for singleton births or with ICD9/10 codes. We used logistic regression models fitted with generalised estimating equations and adjusted for baseline covariates. Results There were 611 pregnancies in 513 women (32±5 years), and 5638 pregnancies in 4077 women (31±5 years) in the csDMARDs exposed and unexposed groups, respectively. We identified 13%, 18%, and 42% of newborns as SGA in unexposed pregnancies and exposed to Group 1 and 2 csDMARDs, respectively. The adjusted odds ratio (OR) for exposure to Group 1 csDMARDs preconception and during pregnancy and risk of SGA births was 1.49 (95%CI 1.12, 1.97) (table 1). The risk of SGA births was higher in those exposed to Group 2 csDMARDs (OR 1.78, 95% CI 1.14, 2.78). With respect to specific csDMARDs, we observed an OR of 1.25 (95% CI, 0.41, 3.82) for methotrexate.Abstract THU0700 – Table 1 Association of csDMARD exposure preconception and/or during pregnancy and risk of SGA births Models* Exposure period OR 95% Confidence Interval Model 1Group 1 csDMARDs Preconception only vs. unexposed 0.79 0.42–1.50 During pregnancy only vs. unexposed 1.57 0.83–2.99 Preconception AND during pregnancy vs. unexposed 1.49 1.12–1.97 Model 2Group 2 csDMARDs Preconception only vs. unexposed 0.85 0.42–1.72 During pregnancy only vs. unexposed 2.65 0.95–7.37 Preconception AND during pregnancy vs. unexposed 1.78 1.14–2.78 Model 3Methotrexate Preconception only vs. unexposed 0.77 0.31–1.88 During pregnancy only vs. unexposed 2.24 0.48–10.48 Preconception AND during pregnancy vs. unexposed 1.25 0.41–3.82 *All models were adjusted for baseline covariates including maternal characteristics, obstetrical history, comorbidities, and medication use before/during pregnancy. Conclusions Our findings suggesting a risk of SGA births with exposure to csDMARDs preconception and during pregnancy have implications for informing women with inflammatory arthritis who are pregnant or planning to become pregnant. Disclosure of Interest None declared