Longitudinal trends in placental stiffness during normal pregnancy: An exploratory strain elastography study

OBJECTIVES: To explore the feasibility of using strain elastography to characterize longitudinal changes in placental stiffness during normal pregnancy and to provide preliminary reference data for future research. MATERIALS AND METHODS: In this prospective pilot study, 80 healthy singleton pregnancies underwent two serial strain elastography evaluations, one in the second trimester and one in the third. Placental color maps were analyzed semiquantitatively to estimate the distribution of relative stiffness regions (red = soft and blue = stiff). Maternal variables, including age, parity, body mass index, and gestational weight gain, were assessed for potential associations with placental stiffness patterns. RESULTS: Placental stiffness patterns shifted toward softer tissue from the second to the third trimester ( P < 0.001), with red areas increasing from 2.3% to 21.0% and blue areas decreasing from 31.0% to 8.1%. Greater maternal weight gain was modestly associated with higher residual stiffness at term ( r = 0.316 and P = 0.047). Multiparous pregnancies demonstrated a nonsignificant trend toward greater softening compared with primigravid cases. CONCLUSION: These findings suggest that strain elastography can detect longitudinal softening trends in normal pregnancies, supporting its feasibility as an exploratory tool. Given the modest sample size and methodological constraints, the results should be interpreted as preliminary. Establishing baseline trends in healthy pregnancies may serve as a reference for future multicenter studies and investigations in high-risk conditions.