A Longitudinal Assessment of Shear Wave Elastography of the Placenta in Normal Pregnancy

This study aimed to use shear wave elastography (SWE) to longitudinally evaluate placental elasticity in normal human pregnancy, and to develop reference ranges for its use at various gestational ages throughout pregnancy.

Data were obtained from a prospective cohort within the Human Placenta Project, involving 90 pregnant participants with uncomplicated singleton gestations. Placental elasticity was measured using SWE at eight distinct gestational time points, from 12 to 37 weeks. Descriptive statistics were reported as median and interquartile for continuous variables, and number and percentage of the total for categorical variables. Distribution of response variables (elastography) were assessed with QQ-plots, skewness, and kurtosis values. Candidate models were compared with likelihood ratio tests.

Out of the 610 pregnant participants initially enrolled, 90 met the criteria for the reference population. Mean SWE values showed a steady increase with advancing gestational age, from 1.283 m per second (m/s) at 12 to 13 weeks to 1.381 m/s at 36 to 37 weeks. Similarly, Young's modulus values increased from 4.99 kPA to 5.59 kPA across the same interval. SWE values were consistent across different placental regions and showed a continuous upward trend with gestational age. Gestational age was significantly associated with SWE values in the central placenta, with fitted reference ranges provided.

SWE is a feasible and reproducible tool for assessing placental stiffness throughout gestation.

· Placental SWE rises steadily from 12 to 37 weeks in normal pregnancy.. · We present gestational age-specific reference ranges for SWE throughout gestation.. · SWE values are consistent across placental regions..