Backgrounds:Given the high prevalence of thyroid disorders during pregnancy and the importance of these disorders in pregnant women and studies on the relationship between thyroid dysfunction during pregnancy and adverse pregnancy outcomes, still there is no consensus on effectiveness of screening all women in early pregnancy regarding thyroid dysfunction and among the international scientific communities recommend the targeted high-risk case finding approach to identify these disorders in pregnancy. The purpose of this study is to compare universal screening with targeted high-risk case finding for diagnosis of thyroid disorders in Iranian pregnant women.

Materials and Methods: The present study is a cross-sectional study that was carried out on 1600 pregnant women in their first trimester. After data collection using questionnaires, their risk status in terms of thyroid disorders was estimated by the check lists of risk factors. Then, their incidence to thyroid disorders was characterized based on clinical examinations and measuring serum levels of T4, TSH, TPOab and T-uptake. The prevalence of thyroid disorders were identified and the predictive risk factors of thyroid disorders were determined by regression analysis.

Results: The study was conducted on 1,600 pregnant women, the prevalence of thyroid disorders was 36.5% (n=584). According to the results of hormonal tests in the high-risk group 42.9% (n = 386) and in the low-risk group 28.3% (198 patients) were diagnosed with a type of thyroid disorders. Among the risk factors, history of thyroid drug use, family history of thyroid disorders and Previous history of a thyroid disorder, were significant prognostic factors (p<0.005).

Discussion: It seems that with lack of universal screening about one-third (33.9%) of women with thyroid disorders are not diagnosed during pregnancy. Further studies are recommended.