Placental Growth during Normal Pregnancy - A Magnetic Resonance Imaging Study

Abstract

Objective: To investigate normal human placental growth longitudinally throughout the second and third trimesters using MRI. Methods: Twenty normal, first-time singleton pregnancies were scanned 7 times between the 14th and 38th week of gestation, at 4-week intervals, using MRI. Placental volumes were measured in both sagittal and transversal slices. All placentas were weighed after delivery to make a comparative study. Results: Sixteen of the 20 women had increasing placental volumes from the 14th to 38th week of gestation. The 6th and 7th scan showed that 4 women had placentas of the same size. The mean placental volume increases linearly from the 14th till the 38th week of gestation, with a constant mean growth rate of 29.97 ml/week. The median placental volume extrapolated to delivery was to 856 ml (range 602-1,050 ml). The median weight of the exsanguinated placenta after delivery was 640 g (range 500-787 g). All pregnancies were carried to term, resulting in the delivery of healthy infants with good correlation between placental size and birth weight (R = 0.56, p = 0.009). Conclusion: Placental growth was measured systematically in a longitudinal study through the second and third trimesters using MRI. MRI provides a safe and feasible method to measure placental growth. The mean placental growth was linear throughout the second and third trimesters.

Human Placenta Blood Flow During Early Gestation With Pseudocontinuous Arterial Spin Labeling MRI

“…The difference between first and second MRI scans was highly significant for the placental volume (156.6 cm 3 ± 53.8 vs. 269.7 cm 3 ± 80.0, P < 0.001) and statistically significant for PBF (104.9 ml/100g/min ± 31.4 vs. 111.3 ml/100g/min ± 25.9, P = 0.02) in normal subjects, indicating an overall development of the placenta along advancing gestational age and its associated increase in blood flow. Note that the longitudinal trajectory of placental volume generally matches that observed in a previous MRI study …”

“…Note that the longitudinal trajectory of placental volume generally matches that observed in a previous MRI study. 36 The differences between normal and IPD subjects for the four imaging parameters are illustrated in Fig. 6 as boxplots.…”

Placental volume in gestational week 27 measured by three‐dimensional ultrasound and magnetic resonance imaging

“…MRI has previously been used to measure placental volume, and the volumes in those studies ranged from 409 to 580 cm 3 in the interval between gestational weeks 26-30. [14][15][16][17][18][19] The median placental volumes in gestational week 27 was around 500 cm 3 , and this finding is in agreement with the median MRI estimated volume in our study. 16,18,19 Our MRI images provided a good overview of the placentas, as well as good soft tissue contrast.…”

“…12,13 MRI images of the uterus provide a good overview of the entire placenta and several previous studies have estimated placental volumes using MRI. [14][15][16][17][18][19] MRI has been shown to measure organ volumes accurately. 20 Hence, we believe that MRI is the best tool available for measuring placental volume in ongoing pregnancies.…”

The Possible Role of Placental Morphometry in the Detection of Fetal Growth Restriction

“…Reference values of placental volume by MRI measurements throughout gestation of healthy pregnancies, although in relatively small sample size, have been studied and are available now (Duncan et al, 2001; Langhoff et al, 2017; León et al, 2018). Current research on placental imaging is much more focused on the more advanced techniques of functional MRI (fMRI), rather than assessment of placental morphometry with conventional MRI.…”