ObjectivesTo investigate pregnancy outcomes in women with axial spondyloarthritis (axSpA) under different pharmacological treatments in comparison with matched controls.MethodsUsing health insurance data from 2006 to 2019, pregnancy outcomes of women with axSpA were compared with those of age-matched and calendar year-matched controls without axSpA. Women with axSpA were further stratified by treatment prior to delivery and pregnancy outcomes compared. Adjusted ORs (aORs) with 95% CIs were calculated using generalised estimating equation analyses.ResultsA total of 1021 pregnancy outcomes in patients with axSpA were identified (928 deliveries, 80 abortions, 13 ectopic pregnancies) and compared with 10 210 pregnancy outcomes in controls (9488 deliveries, 615 abortions, 147 ectopic pregnancies). Compared with controls, women with axSpA showed higher odds of elective caesarean section (aOR 1.52; 1.25 to 1.85).Among women with axSpA, the risk of preterm birth was higher under non-steroidal anti-inflammatory drugs (NSAIDs) treatment (aOR 2.22; 1.09 to 4.52) than without any anti-inflammatory treatment. The risks of preterm birth (aOR 4.01; 1.93 to 8.34) and small-for-gestational-age (aOR 3.22; 1.34 to 7.73) were increased under NSAIDs treatment in combination with conventional synthetic disease-modifying anti-rheumatic drugs (DMARDs), steroids or analgesics. Non-significant increased risks of small-for-gestational-age (aOR 1.68; 0.43 to 6.57) and preterm birth (aOR 1.56; 0.51 to 4.83) were found under biological DMARDs.ConclusionsWomen with axSpA have significantly increased odds of caesarean section compared with matched controls. Risks of preterm birth and small-for-gestational-age vary by type of anti-inflammatory treatment.