The past two decades have witnessed increasing understanding of the molecular pathways and regulation of the three large iron flows in the body: intestinal iron absorption, macrophage-mediated recycling of iron from senescent erythrocytes, and the uptake of iron and its retrieval from storage in hepatocytes. Often forgotten is another large iron flow, the transfer of iron during pregnancy from the mother through the placenta to the fetus. Understanding how the placenta transports iron and how the placental-fetal unit responds to maternal iron stresses is of more than academic interest, as iron deficiency during pregnancy is a major global problem, too often compounded by maternal infection and inflammation. In this context, the recent contributions of Sangkhae et al. JCI 2020 (and the associated commentary by Parrow et al. JCI 2020) and Fisher et al. JCI Insight 2020 are particularly noteworthy.