The main risk is to the newborn baby. Strep B can cause a severe infection which may even be life-threatening. The baby acquires the infection during the birth by inhaling or swallowing vaginal secretions and can be largely prevented if the carrier mother is administered with antibiotics during labour. If the membranes have been ruptured for a prolonged time and Strep-B is in the vagina, there is an increased risk of infection. One woman in five is a carrier but the vast majority of babies are not affected and treatment is reserved for babies who show signs of illness after birth.