Epidemiology of Early-Onset Group B Streptococcal Neonatal Disease in a Tertiary Care Hospital in Korea: A 22-Year Longitudinal Study, 2001–2022

first week of birth (0-6 days) are defined as early-onset disease (EOD), while those developing between one week and three months after birth (7-89 days) are referred as late-onset disease [1, 2].Risk factors for EOD include central venous catheters, other invasive medical devices, prolonged hospitalization, preterm membrane rupture, amnionitis, multiple (more than three) vaginal examinations during labor, maternal fever during labor, or any other infection during labor, and neonates with aspiration of meconium, low, very low, and extremely low birth weights, and preterm birth [3].Most EOD cases result from the ascending spread of GBS colonizing the maternal genitourinary tract into the amniotic fluid [4], which can lead to severe infections such as bacteremia and meningitis [5].Because these GBS EOD infections likely result in severe infection in neonates, intrapartum antibiotic chemoprophylaxis (IAP) was introduced in the United States in 1996