What? This project will explore the maternal immune landscape during pregnancy and postpartum, focusing on a type of immune cells called regulatory T cells, to unravel the mechanisms via which these cells influence pregnancy complications like miscarriages and/or pre-term birth. Why? Complications during pregnancy, such as miscarriages or pre-term births, are not uncommon. These issues are, in fact, a big health concern worldwide. Figuring out how to predict them early in pregnancy is both essential and complex because we do not fully understand what causes them. Fundamental research on the topic is therefore needed to predict and better manage the women/children at risk. How? Using circulating immune cells from pregnant women we will study how regulatory T cells are linked to pregnancy complications via two advanced methods: one looking at the big picture of how immune cell populations change during pregnancy and another zooming into individual cells and their behaviour.