Thyroid-stimulating hormone in pregnancy: are we in need of a lower cutoff value?

Abstract

Background No consensus has been reached regarding the normal range of thyroid-stimulating hormone (TSH) in the first trimester of pregnancy. Aim To determine the effect of TSH levels and thyroid peroxidase antibody (TPOAb) positivity on miscarriage outcome among Egyptian euthyroid women. Materials and methods The study was a prospective case–control study conducted at Al-Azhar University Hospital in New Damietta. It included 80 newly-diagnosed pregnant euthyroid women: 40 women with unexplained recurrent miscarriage, assigned as group 1 (subdivided into two subgroups according to the presence of TPOAb), and a control; group of 40 randomly selected fertile pregnant women who had no history of miscarriage, assigned as group 2. Free T4, TSH, and TPOAb assays were performed at 8-week gestational age. We followed all cases periodically every 4 weeks and when necessary. Results The study revealed significant higher frequency of positive TPOAb in group 1 than group 2 (P=0.045). During the study observation, miscarriage occurred more than two-fold higher in group 1 than group 2 (17.5 vs. 7.5%, respectively, P=0.176) but was significantly higher among TPOAb positive than TPOAb negative women within group 1 (54.5 vs. 3.4% respectively, P Conclusion TPOAb is a useful marker for identifying the risk for miscarriage among Egyptian euthyroid women. The risk was augmented when TSH exceeded 2.5 mU/l in the first trimester of pregnancy, and in the presence of family history of autoimmune thyroid disease.