Newborn babies are highly susceptible to infection because their immune systems do not function as well as those of older children and adults. Children infected at or shortly after birth have much more serious infections, resulting in one million newborns dying each year from infection. The hypothesis is that the newborn's immune system is adapted to survive the fetal period, and that a more well-functioning immune system in the fetus would lead to spontaneous abortion. The aim of the project is to investigate why newborn babies have such a severe disease course when infected with the herpes virus, and whether this is linked to fetal survival in the womb. We are investigating how white blood cells from newborn babies work and how they react when they come into contact with the virus, and comparing this with how cells from adults react. We will also study whether white blood cells can be involved in preterm birth, i.e. premature babies. We do this in the placenta, the part of the uterus that protects the baby from infections and from being attacked by the mother's immune cells. We hope that these studies will enable us to prevent/treat preterm birth and severe herpes virus infections in newborns.