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

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.

A cohort study of 150 women with CTD diagnosed during first trimester of pregnancy and 150 negative controls.

Screening of CTD by a self-reported questionnaire, rheumatic and thyroid autoantibody detection, clinical rheumatological evaluation and obstetric outcomes.

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).

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.