APLN and COVID-19: In brief, the following pathways were altered in the maternal compartments of the placentas from women with COVID-19: Oxidative phosphorylation, insulin secretion, cortisol synthesis and secretion, estrogen signaling, antigen processing and presentation, GnRH secretion, endocrine and other factor-regulated calcium reabsorption, oxytocin signaling, fatty acid elongation, GnRH signaling, apelin signaling, and growth hormone synthesis, secretion, and action.