Angiogenesis is required for embryonic development and growth for successful hemochorial placentation (for recent reviews, see [23, 42] ). Distinct vascular processes occur during pregnancy, starting with adaptations of the endometrial vasculature to support blastocyst implantation, followed by expansion and de novo formation of blood vessels to support embryo growth and development. Even at later stages of pregnancy, the placental vasculature continues to be remodeled to enable blood flow to the increasing metabolic demands of the fetus. Sufficient uteroplacental blood flow requires remodeling of the spiral arteries by the extravillous trophoblasts [43] . Failure of spiral artery remodeling has been associated with complications of pregnancy, such as preeclampsia and fetal growth restriction [44] [45] [46] . Therefore, a better understanding of the stimuli needed for cell production of angiogenic growth factors during the processes of uteroplacental vascular remodeling and the generation of the placental vascular network is of major clinical interest.