An effective analysis of screening strategies for thyroid disorders during early pregnancy

Abstract

Objective To use the first trimester-specific reference intervals of thyroid-related hormones to explore the prevalence of thyroid dysfunction during early pregnancy and to analyze effectiveness of different screening strategies. Methods In this study 2 899 pregnant women were enrolled during the first trimester of gestation. TSH, FT4, FT3, and thyroid peroxidase antibody （TPOAb） were measured and thyroid disorders of pregnant women were diagnosed based on the first trimester-specific reference intervals. Results The prevalence of hypothyroidism was significantly higher in the high-risk group than in the non-high risk group （ 16.3% vs 5.3%,RR = 3.1,95% CI 2.4-4.0, P〈0.01 ）. TPOAb （ RR = 4.7, 95 % CI 3.6-6.0, P〈0.01 ）, and personal history of thyroid diseases （ RR=3.2, 95% CI 1.9-5.4, P〈0.01 ） increased the risk of hypothyroidism. The prevalence of hyperthyroidism was higher in the high-risk group （3.1% vs 1.4%, P = 0. 006, RR = 2.2, 95% CI 1.2-3.9, P=0.006）. TPOAb （RR=2.6, 95%CI 1.3-5.0, P=0.007）, and presence of personal history of thyroid diseases（ RR=4.7, 95% CI 1.7-12.5, P=0.006） also increased the risk of hyperthyroidism. 56.7% women with hypothyroidism and 64. 7% women with hyperthyroidism were in the non-high risk group. Conclusion We recommend that screening all pregnant women for thyroid disorders in the first trimester with TSH, FT4, and TPOAb is more effective than the case-finding approach. Key words: First trimester pregnancy ; Screening; Thyroid dysfunction ; Risk factors