European Journal of Endocrinology www.eje-online.org © 2017 European Society of Endocrinology Printed in Great Britain Published by Bioscientifica Ltd. DOI: 10.1530/EJE-16-0548 Effects of levothyroxine treatment on pregnancy outcomes in pregnant women with autoimmune thyroid disease Sima Nazarpour 1,3 , Fahimeh Ramezani Tehrani 2 , Masoumeh Simbar 3 , Maryam Tohidi 4 , Hamid Alavi Majd 5 and Fereidoun Azizi 6 1 Department of Midwifery, Faculty of Nursing and Midwifery, Islamic Azad University, Varamin-Pishva Branch, 2 Reproductive Endocrinology Research Center, Research Institute for Endocrine Sciences, 3 Department of Reproductive Health and Midwifery, Faculty of Nursing and Midwifery, 4 Prevention of Metabolic Disorders Research Center, Research Institute for Endocrine Sciences, 5 Department of Biostatistics, Faculty of Paramedicine, and 6 Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences and Health Services, Tehran, Iran Abstract Background: Despite some studies indicating that thyroid antibody positivity during pregnancy has been associated with adverse pregnancy outcomes, evidence regarding the effects of levothyroxine (LT4) treatment of euthyroid/ subclinical hypothyroid pregnant women with autoimmune thyroid disease on pregnancy outcome is limited. We aimed to assess whether pregnant women with autoimmune thyroid disease, but without overt thyroid dysfunction are affected by higher rates of adverse pregnancy outcomes. In addition, we aimed to explore whether LT4 treatment improves the pregnancy outcome of affected women. Methods: A prospective study was carried out on pregnant women from the frst trimester to delivery. The study was conducted among pregnant women receiving prenatal care in centers under coverage of Shahid Beheshti University of Medical Sciences. Of a total of 1746 pregnant women, screened for thyroid dysfunction, 1028 euthyroid TPOAb- negative (TPOAb − ) and 131 thyroid peroxidase antibody-positive (TPOAb + ) women without overt thyroid dysfunction entered the second phase of the study. TPOAb + women were randomly divided into two groups: group A (n = 65), treated with LT4 and group B (n = 66), received no treatment. The 1028 TPOAb − women (group C) served as a normal population control group. Primary outcomes were preterm delivery and miscarriage and secondary outcomes included placenta abruption, still birth, neonatal admission and neonatal TSH levels. Results: Groups A and C displayed a lower rate of preterm deliveries compared with group B (RR = 0.30, 95% CI: 0.1–0.85, P = 0.0229) and (RR = 0.23, 95% CI: 0.14–0.40, P < 0.001) respectively. There was no statistically signifcant difference in the rates of preterm labor between groups A and C (RR = 0.79, 95% CI: 0.30–2.09, P = 0.64). The number needed to treat (NNT) for preterm birth was 5.9 (95% CI: 3.33–25.16). Conclusions: Treatment with LT4 decreases the risk of preterm delivery in women who are positive for TPOAb. Introduction Thyroid disorders, especially those of autoimmune origin, are common in women of reproductive age (1, 2). Although the complications of overt hypothyroidism or hyperthyroidism on pregnancy outcomes, and neonatal and childhood development are well known (3), there is still no consensus on the association between subclinical 176:2 253–265 S Nazarpour and others Levothyroxine treatment in TPOAb + pregnant women European Journal of Endocrinology (2017) 176, 253–265 Clinical Study Correspondence should be addressed to F Ramezani Tehrani Email ramezani@endocrine.ac.ir or framezan@post.harvard.edu Downloaded from Bioscientifica.com at 06/07/2020 02:51:03AM via free access