For the first time, scientists have created detailed maps of immune cells in the placenta. These maps provide insights into how the immune system defends the fetus from infections during early pregnancy. By studying these maps, researchers hope to develop treatments that prevent pregnancy complications caused by infections. The placenta acts as a barrier between the mother and fetus, allowing essential substances like nutrients to pass through while blocking harmful substances like germs. However, during early pregnancy, the fetus’s immune system is still developing, making it vulnerable to infections.