Measuring intrauterine growth in healthy pregnancies using quantitative magnetic resonance imaging

OBJECTIVE: The aim of this study was to determine in utero fetal-placental growth patterns using in vivo three-dimensional (3D) quantitative magnetic resonance imaging (qMRI). STUDY DESIGN: Healthy women with singleton pregnancies underwent fetal MRI to measure fetal body, placenta, and amniotic space volumes. The fetal-placental ratio (FPR) was derived using 3D fetal body and placental volumes (PV). Descriptive statistics were used to describe the association of each measurement with increasing gestational age (GA) at MRI. RESULTS: Fifty-eight (58) women underwent fetal MRI between 16–38 completed weeks gestation (mean=28.12±6.33). PV and FPR varied linearly with GA at MRI (rPV,GA=0.83,rFPR,GA=0.89, p value<0.001). Fetal volume varied non-linearly with GA (p-value < 0.01). CONCLUSIONS: We describe in-utero growth trajectories of fetal-placental volumes in healthy pregnancies using qMRI. Understanding healthy in utero development can establish normative benchmarks where departures from normal may identify early in utero placental failure prior to the onset of fetal harm.