Unfortunately in my years of practice in the NICU I know of babies who have died from GBS infection. If you refuse and the baby shows any questionable symptoms after birth I put an IV in your kid and give them anyway. Actually had a mom refuse for her infant once (who hadn't had them in labor and was showing signs of infection). We worked really hard to convince her to let us treat the newborn but she continued to refuse even as the baby's condition was worsening. We ended up contacting CPS and got legal custody of the baby and gave it antibiotics anyway. And then she had the joy of dealing with the county regarding her ability to provide safe care for her infant.