Abstract

Pregnancy success requires constant dialogue between the mother and developing conceptus. Such crosstalk is facil-itated through complex interactions between maternal and fetal cells at distinct tissue sites, collectively termed the "maternal -fetal interface." The emergence of single-cell technologies has enabled a deeper understanding of the unique processes taking place at the maternal -fetal interface as well as the discovery of novel pathways and immune and nonimmune cell types. Single-cell approaches have also been applied to decipher the cellular dynamics through-out pregnancy, in parturition, and in obstetrical syndromes such as recurrent spontaneous abortion, preeclampsia, and preterm labor. Furthermore, single-cell technologies have been used during the recent COVID-19 pandemic to eval-uate placental viral cell entry and the impact of SARS-CoV-2 infection on maternal and fetal immunity. In this brief review, we summarize the current knowledge of cellular immunobiology in pregnancy and its complica-tions that has been generated through single-cell investi-gations of the maternal -fetal interface. The Journal of Immunology, 2022, 209: 1450-1464.