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.