Prevalence of undiagnosed autoimmune rheumatic diseases in the first trimester of pregnancy. Results of a two‐steps strategy using a self‐administered questionnaire and autoantibody testing

Objective To evaluate the prevalence of undiagnosed rheumatic diseases in the first trimester of pregnancy. Design We screened for rheumatic diseases in 1210 consecutive pregnant women during the first trimester of pregnancy using a 10‐item questionnaire. Setting A university hospital in northern Italy. Population One hundred and thirty‐seven (11.3%) women who answered positively to at least one question constituted the cases and were compared with 107 negative controls. Methods Cases and controls were tested for rheumatic autoantibodies (antinuclear antibody, anti‐double‐stranded DNA, anti‐extractable nuclear antigen, anticardiolipin antibody, anti‐β2‐glycoprotein I antibodies and lupus anticoagulant) and were evaluated by a rheumatologist for a definite diagnosis of rheumatic disease. Main outcome measures Prevalence of undiagnosed rheumatic disease in the first trimester of pregnancy. Results The overall rate of positivity to the antibodies tested was 43.1% (59/137) among cases and 9.3% (10/107) in the controls ( P < 0.001). A definitive diagnosis of rheumatic disease was made in 35 cases (25.5%) and in none of the controls ( P <0.001). In stepwise logistic regression analysis, photosensitivity (adjusted OR 5.72; 95% CI 2.38–13.8), erythema or malar rash (adjusted OR 3.91; 95% CI 1.53–10) and history of two or more miscarriages (adjusted OR 5.6; 95% CI 1.55–20.6) were independent predictors of a definitive diagnosis of rheumatic disease (area under receiving operator curve = 0.814; 95% CI 0.76–0.86). Birthweight was lower (3180 g ± 475 compared with 3340 g ± 452, P = 0.008), and overall serious pregnancy complications (miscarriage, fetal growth restriction, delivery before 34 weeks of pregnancy and severe pre‐eclampsia) were higher among cases (12/137) than controls (2/107) (adjusted OR 5.60; 95% CI 1.29–24.3; P = 0.021). Conclusions A two‐step screening process with a self‐administered questionnaire proved to be a useful method to screen for undiagnosed rheumatic diseases during the first trimester of pregnancy.