Introduction The impact of thyroid autoimmunity in pregnancy on neonatal outcomes remains unclear. Studies to date have revealed a positive correlation between thyroid antibodies and preterm births and miscarriages. However other aspects of neonatal outcomes need further exploration. Advanced maternal age is associated with the escalation of the prevalence of thyroid antibodies. Not only this, advanced maternal age in itself is a proven factor for unfavourable fetal outcomes. Most of the studies to date in this regard have an age-related bias as women of all groups were included to assess the neonatal outcomes in women with thyroid antibodies. Our study was conducted in hypothyroid women who were less than 35 years of age with thyroid antibodies to assess outcomes on the neonates unbiased of advanced maternal age. Hypothesis To evaluate the effects of maternal thyroid autoimmunity on neonatal outcomes. Methodology A retrospective chart review was conducted on 7978 women delivered in the study timeline in a secondary hospital of Qatar. 287 women were hypothyroid and out of these 198 women with age less than 35 years were included in the study. Neonatal outcomes such as preterm births, small for date babies, admission to neonatal intensive care units (NICU) and intrauterine fetal deaths (IUFD) were noted and compared with 200 euthyroid women who were selected by random sampling. Statistical Package for the Social Sciences version 27. 0 was used for statistical analysis. The Odds’ ratio was calculated and results with a value of p<0. 05 was considered significant. Results Thyroid autoimmunity was noted in 30.30% of hypothyroid pregnant women. All these women had thyroid peroxidase antibody and thyroglobulin antibody was observed in 4.44%. The range of TPO antibodies was 67-1350 IU/ml (mean 497 IU/ml). 10% vs 4.5% (OR- 2.22, 95%CI-0.760 to 6.495, P = 0.14) preterm births and 10% vs 3% (OR-3.33, 95%CI-1. 037-10.71, p<0. 05) small for dates babies were observed in women with thyroid antibodies in comparison to the control (euthyroid pregnant women). Higher incidence of NICU admissions (22% Vs 8.5%, p<0. 05) and IUFD rates (5% Vs 0.5%, p<0. 05) were noted in women with thyroid autoimmunity. Conclusion This study demonstrates the detrimental effects of thyroid autoimmunity on neonates of hypothyroid women less than 35 years of age. In this age group of hypothyroid women, testing for thyroid immunity should be considered. Antenatal fetal surveillance is advisable in the presence of thyroid antibodies. References: Roberto Negro, Alan Schwartz, Riccardo Gismondi, Andrea Tinelli, Tiziana Mangieri, Alex Stagnaro-Green, Thyroid Antibody Positivity in the First Trimester of Pregnancy Is Associated with Negative Pregnancy Outcomes, The Journal of Clinical Endocrinology & Metabolism, Volume 96, Issue 6, 1 June 2011, Pages E920–E924. Stagnaro-Green, A. et al. (2005). The thyroid and pregnancy: a novel risk factor for very preterm delivery. Thyroid,15(4), 351-357. Presentation: No date and time listed