Background Ankylosing spondylitis (AS) often starts in fertile age and is characterized by back pain, local and systemic inflammation, and may require systemic treatment.
Objectives Other chronic inflammatory diseases, such as inflammatory bowel disease and rheumatoid arthritis affect pregnancy and birth outcomes, but for AS this has not been studied, which was the aim of this study.
Methods We performed a, nationwide, registry- and population-based care-control study. Cases were identified by diagnosis of an ICD code for AS in the Swedish national patient register at a visit to a specialist in rheumatology or internal medicine. For each index case 5 controls were identified matched for birth year, time and county at first AS diagnosis. Data on cases and controls were linked to the Medical Birth Register (MBR) for identification of first pregnancy and related birth outcomes and to Statistics Sweden (educational level). Cases and matched controls were included if they had their first singleton birth after inclusion, i.e. after diagnoses of AS for cases. Relative risks were assessed using conditional logistic regression models.
Results In total, we identified 172 first time singleton deliveries among women with a history of a diagnosis of AS from 2001 and onwards before delivery, and 469 deliveries among the matched general population controls. Caesarean section was more common and pregnancies tended to be of shorter gestational age in AS patients compared to controls. Adjustment for smoking habits, BMI and educational level did not change point estimates of relative risk.
Sensitivity analyses restricted to women with AS diagnosis before start of gestation resulted in similar point estimates.
Conclusions Women with AS had increased risk of being delivered with Caesarean section, both planned and acute and had a tendency for preterm birth.
Disclosure of Interest : None declared