Materials and Methods
The inclusion criterion was thai pregnant women who are in clinical euthyroid status which identified by history and physical examination by obstetricians during August to October 2008. After exclusion, there were 480 pregnant women enrolled in this study which consisted of 134 in the first trimester, 184 in the second trimester and 162 in the third trimester of pregnancy. Serum samples were obtained as a part of their routine antental screening at ramathibodi hospital and stored at-200C until analyzed. TSH and TPO-Ab were measured by Chemiluminescent Microparticle immunoassay (ARCHITECT; Abbott Park,IL, USA). Reference range of TSH is brtween 0.35 and 4.94 mIU/L. TPO-Ab level more than 5.61 IU/mL was determined as “positive”. Statistical data were analyzed using Microsoft Excel and SPSS version 12 for Windows.