MATERNAL PREPREGNANT WEIGHT AND WEIGHT-GAIN - RELATIONSHIP TO PLACENTAL MICROSTRUCTURE AND MORPHOMETRIC OXYGEN DIFFUSION CAPACITY

This study examines the effects of maternal prepregnant weight and ges tational weight gain on the size, microstructure, and function of the human placenta. Standard gross, histologic, and histomorphometric tech niques were used to examine placentas obtained from the deliveries of 77 poor, black 12- to 30-year-old subjects in relation to maternal pre pregnant weight and the rate of maternal weight gain during gestation. The weight, volume, and fetal capillary surface area of the placenta increased significantly in relation to both maternal prepregnant weigh t and the rate of maternal weight gain during gestation. Prepregnant w eight was a more important determinant of placental size and fetal cap illary surface area than was the rate of maternal weight gain. The rat e of maternal weight gain was a more important determinant of the dens ity of fetal capillary tissues within the placenta and of placental re sistance to oxygen diffusion than was prepregnant weight. Both materna l prepregnant weight and the rate of maternal weight gain during gesta tion relate positively to the size of the placenta, but they have diff erent, potentially complementary effects on placental microstructure a nd function.