LAUSR

PURPOSE We aimed to determine the volume of the thyroid gland in full-term neonates born to hypothyroid mothers as compared with full-term infants born to healthy mothers and to investigate the association between levothyroxine doses and the thyroid volume of neonates. MATERIALS AND METHODS This is single center prospective observational study of 245 full-term neonates (96 from hypothyroid and 149 from healthy mothers). Ultrasound examination in both longitudinal and transverse projections was used to calculate the thyroid volume applying the ellipsoid formula. RESULTS Median (interquartile range) thyroid volume of newborns from hypothyroid mothers was significantly smaller compared to the control group with regard to the total thyroid volume and the left lobe (p < 0.05). We found no statistically significant difference for the right lobe (p > 0.05) and inverse correlation between the thyroid volume and levothyroxine doses taken by mothers. CONCLUSION Results of the present study indicate that maternal thyroid hormone levels may interfere with the fetal hypothalamic-pituitary axis.