Objective: First trimester thyroid-stimulating hormone (TSH) level is an important determiner of neonatal outcome. In this study we investigated the relationship between first-trimester TSH level and fetal birthweight. Materials-Methods: First-trimester serum TSH, age, gravidity, parity, body mass index (BMI), gestational age, and birth weight were analyzed. Patients were divided two ways. The first division- group 1 with TSH < 2.5 mU/l, group 2 with TSH > 2.5 mU/l). The second division- group 3 with TSH < 4 mU/l and group 4 with TSH > 4 mU/l). Results: The study included 302 patients. High TSH levels are associated with an increased risk of macrosomic and post-term babies. A significant association was found for both thresholds of 2.5 and 4.0 mU/l. However, this relation was not significant after binary logistic regression. Conclusion: High maternal first trimester TSH levels are not associated with birth weight after separating out macrosomia-related factors.
Keywords: Birthweight; postterm; pregnancy; thyroid function.