Maternal obesity during pregnancy is often characterized by fetal macrosomia but it can also result in fetal growth restriction in a subset of pregnancies. We hypothesized that mechanisms of this growth restriction may include adverse effects of maternal high fat (HF) intake on placental growth and function. Female rats (100 days old) were time-mated and randomly assigned to either a control (Con) or HF diet
ad libitumthroughout gestation. At E21, dams were killed; litter size and fetal and placental weights were recorded and maternal and fetal samples collected for further analyses. The HF diet resulted in a 54% increase in maternal body weight gain during gestation. In contrast, male and female fetal weights were reduced in HF pregnancies ( P< 0.05), as were the weights of the junctional zone of the placenta ( P= 0.013), whereas labyrinth zone weights were unaffected. The HF diet increased maternal and fetal plasma leptin levels ( P< 0.05), but maternal and fetal insulin and fetal glucose levels were unaffected. Labyrinthine expression of PPARγ and total VEGFa mRNA, both markers of placental vascular development, were unaffected by consumption of the HF diet in placentas of male and female fetuses. Furthermore, maternal HF nutrition did not alter phosphorylated protein levels of either mammalian target of rapamycin or its downstream signaling factor eIF4E binding protein 1 (4E-BP1). These data show that in the rat, maternal HF nutrition results in fetal and placental junctional zone growth restriction, maternal and fetal hyperleptinemia but did not alter gene expression of markers of placental vascular development.