The updated Guidelines on Prevention of Perinatal Group B Streptococcal Disease, issued by the Centers for Disease Control and Prevention, actually represent the mainstay in the prevention of neonatal early-onset group B streptococcal (GBS) sepsis. According to these guidelines, patients with possible preterm delivery are screened for GBS colonization and offered intrapartum prophylaxis only if they enter preterm labor or experience preterm premature rupture of the membranes. Nonetheless, the fulfillment of these recommendations seems to be suboptimal in clinical practice, as it is heavily influenced by the knowledge of the colonization status. We report here 2 cases of blood culture-proven, early-onset neonatal GBS sepsis involving preterm infants delivered by mothers who had midtrimester cervical insufficiency and bulging membranes. Midtrimester acute cervical insufficiency strongly predicts preterm delivery. These women are liable to miss intrapartum antibiotic prophylaxis because they typically have shorter labor, and the test results for GBS status are unlikely to be available before delivery. We believe that women with midtrimester cervical insufficiency and bulging membranes should be screened for GBS infection soon after hospital admittance if the gestational age is close to the threshold of fetal viability. A timely diagnosis of GBS colonization may not only increase the number of patients receiving targeted intrapartum antibiotic prophylaxis but would also allow consideration of the administration of antepartum antibiotic prophylaxis. Indeed, as further outlined in this report, GBS intraamniotic infection may dramatically occur before the onset of preterm labor or preterm premature rupture of the membranes.