PGP and obesity due to melanocortin 4 receptor deficiency: Since near pregnancy day 15 corresponds with human gestation week 20, and preeclampsia typically occurs after 20 weeks of pregnancy, our hypothesis is that the obesity-induced reduction of placental P-gp expression on gestation day 15 in rats is probably similar in humans near pregnancy week 20, which presumably contributes to the development of preeclampsia in obese mothers via the previously discussed processes.