Fig. 1

Frame-wise displacement (FD) over time. Motion fluctuation during scans in 3 representative fetuses: low, moderate, and high motion shown in the top, mid, and bottom panels, respectively. Scans exhibited periods of low head motion (< 0.5 mm) interspersed with shorter intervals of higher head movement (e.g., > 1.5 mm). The frequency and intensity of these intermittent high-motion periods varied among scans. For instance, head motion spikes (> 1.5 mm) in the low-motion scan (top panel) occurred only four times (~ 3.6% of scans) compared to more than ten times (~ 22.1% of scans) in the high-motion scan (bottom panel). The average and standard deviation of FD for low-, moderate-, and high-motion scans were 0.42 mm ± 0.42 mm, 0.72 ± 0.65, and 1.15 ± 1.45, respectively.