The war on germs, which uses antibiotics indiscriminately and keeps babies and children from exposure to the real world of germs, has created a generation of children with poor immune systems. The latest evidence comes from a study by the Children’s Hospital of Philadelphia, where researchers found that when pregnant women take antibiotics, this can depress the immune system of their offspring. By contrast, moms can help strengthen a child’s ability to avoid illness by passing on certain germs. The study showed that bacteria in the gut play a crucial role in fostering the rapid production of infection-fighting white blood cells. The researchers found that mice have a surge of white blood cells around birth, but this response is reduced when their mothers are exposed to antibiotics. The offspring of mothers given antibiotics were more vulnerable to deadly E. coli infections, especially when they were born prematurely. Unfortunately, not only are moms routinely given antibiotics—if they test positive for Strep, for example, or have a Cesarean section—critically ill babies are often treated with antibiotics as a precaution without proof of infection (Nature Medicine 20, 469–470 (2014).