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.
The teratogenic potential of diphenylhydantoin sodium (DPH) was investigated in the rabbit after oral intubation of 0 (Control), 25, 50, 75, 100, and 150 mgkglday from days 7-18 of gestation. Except for reduced maternal weight gains at the two higher dosages, no other obvious pharmacological or toxic effects were noted in treated rabbits.Dose-response-related increases in the resorption and malformation rates were observed. Four litters (one of 14 litters with viable fetuses at 75 mglkglday and three of eight litters with viable fetuses at 100 mgkg/day) exhibited a similar pattern of multiple malformations that included some or all of the following defects: open eyes, cleft palate, and limb abnormalities that included shortened and curved long bones, pes caves, syndactyly, and ossification defects of the phalanges. Dosages of 150 mglkglday produced nearly complete resorption, which may have masked the teratogenic response to the drug.
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