In a mouse model, however, maternal placental HIF-1α protein was elevated by maternal obesity (Fernandez-Twinn et al., 2017), supporting the hypothesis that obesity during pregnancy is associated with placental hypoxia, resulting in an induction of angiogenesis to enhance fetoplacental vascular growth (Desoye, 2018). Here, HIF1A is linked to obesity due to melanocortin 4 receptor deficiency.