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.
Keywords: Hypothyroidism of pregnancy; Newborn; Thyroid sonography; Treatment with levothyroxine.
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