For clinicians

Axial spondyloarthritis (axSpA)

axSpA, ankylosing spondylitis, AS

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Bottom lineBottom line: axSpA does not reliably improve in pregnancy and disease activity often peaks in the second trimester; postpartum flare is common. NSAIDs may be used earlier then stopped before the third trimester; TNF inhibitors are frequently continued for active disease. Watch for a modest increase in preterm birth.

By domain

Will pregnancy affect axSpA? ●●●○moderate evidenceconditional

Ursin 2018 (RevNatus, verified primary text): in 179 pregnancies (166 women), BASDAI was low and stable from preconception to 12 months postpartum, peaking in the second trimester (mean 3.97 vs 3.46 at 6 weeks postpartum, P=0.005), when 45% had active disease (BASDAI >=4). Contrary to older retrospective reports of ~60% postpartum flare, this prospective cohort found lower activity postpartum, though many women restarted NSAIDs/TNFi, confounding the natural course.^[3]

Will axSpA affect the pregnancy? ●●○○low evidenceconditional

Associated with a modest increase in preterm birth and possibly caesarean delivery; overall outcomes are generally good.^{[1, 3]}

Fertility ●●○○low evidenceconditional

Fertility is generally preserved; counsel on NSAID effects on ovulation when actively trying to conceive.^[1]

Medicines ●●●○moderate evidenceconditional

NSAIDs short-term earlier in pregnancy, stopped by ~third trimester; TNF inhibitors frequently continued (certolizumab convenient near term). Conventional synthetic DMARDs have limited axial efficacy.^{[1, 2]}

Staying active and comfortable ●●○○low evidenceconditional

Non-pharmacological management (physiotherapy, activity, posture) is central in axSpA and especially valuable when medication options are constrained. Physical function (BASFI) is typically worst in the third trimester even though disease activity peaks in the second (Ursin 2018), so function-focused support matters late in pregnancy.^[3]

After birth ●●○○low evidenceconditional

Unlike RA, the largest prospective cohort did not find a clear postpartum flare in axSpA (Ursin 2018); resume TNFi and compatible therapy guided by symptoms. Most options are breastfeeding-compatible.^{[2, 3]}

Key points

Point	Evidence
Counsel that axSpA often does not remit in pregnancy, unlike RA; plan active management.^[3]	●●●○moderate evidenceconditional
TNF inhibitors are the principal option for active axSpA through pregnancy.^[2]	●●●○moderate evidenceconditional

Key numbers

Ursin 2018: 45% had active disease (BASDAI >=4) in the second trimester, the peak time point; overall course low and stable.^[3]

References

Sammaritano LR, et al. 2020 ACR Guideline for the Management of Reproductive Health in RMD. Arthritis Rheumatol. 2020;72(3):529-556. https://acrjournals.onlinelibrary.wiley.com/doi/10.1002/art.41191
Ruegg L, et al. EULAR recommendations for antirheumatic drugs in reproduction, pregnancy, and lactation: 2024 update. Ann Rheum Dis. 2025;84(6):910-926. https://ard.eular.org/article/S0003-4967(25)00818-0/fulltext
Ursin K, Lydersen S, Skomsvoll JF, Wallenius M. Disease activity during and after pregnancy in women with axial spondyloarthritis: a prospective multicentre study. Rheumatology (Oxford). 2018;57(6):1064-1071. https://doi.org/10.1093/rheumatology/key047