Connective tissue diseases and autoimmune thyroid disorders in the first trimester of pregnancy

OBJECTIVE: To investigate the rates and coexistence of autoimmune thyroid and connective tissue diseases (CTD) during the first trimester of pregnancy and their influence on pregnancy outcome. STUDY DESIGN: A cohort study of 150 women with CTD diagnosed during first trimester of pregnancy and 150 negative controls. MAIN OUTCOME MEASURES: Screening of CTD by a self-reported questionnaire, rheumatic and thyroid autoantibody detection, clinical rheumatological evaluation and obstetric outcomes. RESULTS: Out of 3852 women screened, 61 (1.6%) were diagnosed with undefined connective tissue disease (UCTD), 28 (0.7%) with major CTD (six rheumatoid arthritis, five systemic lupus erythematosus, eight Sjogren syndrome, five anti-phospholipid syndrome, two systemic sclerosis, one mixed CTD and one monoarticular arthritis) and 61 (1.6%) had insufficient criteria for a diagnosis of a rheumatic disease. The overall prevalence of either thyroid peroxidase (TPO-a) or thyroglobulin (TG-a) autoantibodies detection was 8% (12/150) among controls, 62.3% (38/61) among UCTD and 60.7% (17/28) in women with a major CTD (p<.001 compared to controls for both comparisons). After adjustment for confounders, overall CTDs (major or undefined) (OR=3.54, 95% CI; 1.61-7.78) and TPO-a plus TG-a positivity (OR=2.78, 95% CI;1.29-5.98) were independently associated with increased risks of moderate-severe complications of pregnancy (miscarriage, fetal growth restriction, preeclampsia, delivery before 34 weeks). CONCLUSIONS: Rheumatic and thyroid autoantibodies during pregnancy are closely associated. Thyroid antibodies could add to the risk of adverse pregnancy outcome associated with connective tissue diseases.