Risk of pre-eclampsia and impact of disease activity and antirheumatic treatment in women with rheumatoid arthritis, axial spondylarthritis and psoriatic arthritis: a collaborative matched cohort study from Sweden and Denmark

Objective To explore the risk of pre-eclampsia in rheumatoid arthritis (RA), axial spondyloarthritis (AxSpA) and psoriatic arthritis (PsA), focusing on the impact of treatment and disease activity. Methods We identified RA, AxSpA and PsA singleton pregnancies (2006-2018) by linking medical birth registers to Swedish (SRQ) and Danish (DANBIO) rheumatology registers. Control pregnancies from the medical birth registers were matched 1:10 on maternal age, parity and birth year. We obtained information on antirheumatic treatment before and during pregnancy and disease activity during pregnancy. Risks of pre-eclampsia in RA, AxSpA and PsA pregnancies, compared with control pregnancies, were estimated overall and by antirheumatic treatment (conventional synthetic disease-modifying antirheumatic drug (DMARD)/biological DMARD/corticosteroids, as monotherapy or combination therapy) and disease load (Health Assessment Questionnaire≥1/C-reactive protein≥10/Disease Activity Score in 28 joints≥3.2) through logistic regression (adjusted ORs (aORs) with 95% CI). Results We observed 69, 34, and 26 pre-eclampsia events among RA (n=1739), AxSpA (n=819) and PsA (n=489), resulting in a risk of pre-eclampsia of, respectively, aOR 1.27 (95% CI 0.96 to 1.67), 1.17 (0.76 to 1.78) and 1.85 (1.10 to 3.12), compared with controls. For RA, maternal combination therapy before and during pregnancy was associated with increased risk (1.59; 1.07 to 2.37 and 1.53; 0.97 to 2.39, respectively). For PsA, maternal monotherapy before pregnancy was associated with pre-eclampsia (2.72; 1.4 to 5.13). In RA pregnancies with available information (43%), high disease load was associated with doubled risk of pre-eclampsia (aOR 1.96; 1.26 to 3.04). Conclusion PsA pregnancies, but not AxSpA pregnancies, were at increased risk of pre-eclampsia. For RA, combination therapy (potentially a surrogate for high disease activity both before and during pregnancy) and high disease load during pregnancy might be a risk factor for pre-eclampsia.