Which of the following statements about Group B Streptococcus (GBS) in pregnancy is true?

B GBS is a common bacterium found in the vaginal flora of women and is harmless in all cases C Screening for GBS is typically performed at the first prenatal visit D Intravenous antibiotics during labor are recommended for GBS-positive mothers to prevent neonatal infection A GBS can only be transmitted to the baby during cesarean delivery