Background: During pregnancy, numerous changes occur in thyroid gland functions. Ultrasonography (US) is one of the primary imaging methods used for thyroid gland examination. Two-dimensional shear wave elastography (2D-SWE) is an imaging method that allows the quantitative evaluation of the stiffness of tissues, and its use in thyroid gland diseases is gradually increasing. Objectives: The present study aimed to investigate whether there are changes in thyroid parenchymal stiffness during pregnancy and to determine normal 2D-SWE values of the thyroid gland in each trimester. Patients and Methods: Forty-eight healthy pregnant women were evaluated. The dimensions of thyroid lobes were measured separately, and volume values were calculated. The 2D-SWE measurements were made by drawing a circular region of interest (ROI) in the axial plane for both thyroid lobes. Results: The mean age was 28.4 ± 6.0 years. The mean elasticity values (kPa) for the three trimesters were 8.77 ± 1, 8.1 ± 0.7, and 7.6 ± 0.7. Mean velocity values (m/s) were 1.71 ± 0.1, 1.64 ± 0.08, and 1.60 ± 0.07. Total thyroid volume values (mL) were 9.72 ± 4.21, 10.69 ± 4.55, and 11.75 ± 5.2. The 2D-SWE elasticity and velocity values significantly decreased across trimesters (P < 0.05), whereas thyroid volume showed a non-significant trend toward increase. Conclusion: Our study is one of the few longitudinal prospective studies in the literature in which the thyroid gland was evaluated sonographically in pregnant women. We quantitatively demonstrated, with objective numerical data, a significant decrease in thyroid elastography values during pregnancy, while thyroid volume exhibited a non-significant tendency to increase.