Can Group B Streptococcus (GBS) be transmitted to the newborn during a cesarean section (C-section)?

Group B Streptococcus Transmission During Cesarean Section

GBS transmission to newborns during cesarean section is unlikely when the procedure is performed before labor onset and with intact amniotic membranes, regardless of maternal GBS colonization status or gestational age. 1

Risk of GBS Transmission in Different Delivery Scenarios

Cesarean Delivery Before Labor with Intact Membranes

• Intrapartum antibiotic prophylaxis to prevent early-onset GBS disease is not recommended for cesarean deliveries performed before labor onset on women with intact amniotic membranes 1
• This applies regardless of:
  • GBS colonization status of the mother
  • Gestational age of the pregnancy 1
• These infants are considered at low risk for early-onset GBS disease 1

Cesarean Delivery After Labor Onset or Membrane Rupture

• GBS-colonized women who undergo cesarean delivery after labor onset or rupture of membranes should receive intrapartum antibiotic prophylaxis 1
• The risk of vertical transmission increases once labor begins or membranes rupture, as this allows ascending infection from the colonized vagina

Maternal GBS Screening and Management

Despite the low risk during pre-labor cesarean with intact membranes:

• All pregnant women should still undergo routine GBS screening at 35-37 weeks' gestation 1, 2
• This is because labor or membrane rupture can occur unexpectedly before a planned cesarean delivery 1

Key Points About GBS Transmission

• GBS colonizes the gastrointestinal tract and vagina in 10-30% of pregnant women 1, 3
• Vertical transmission primarily occurs after labor onset or membrane rupture 1
• Women with prenatal GBS colonization are >25 times more likely to deliver infants with early-onset GBS disease compared to women with negative cultures 2
• The standard perioperative antibiotics given for cesarean delivery should not be altered based on GBS status 1

Important Caveats and Exceptions

• If any of these conditions develop before a planned cesarean, intrapartum prophylaxis is indicated for GBS-positive women:

  • Onset of labor
  • Rupture of membranes 1

• Other absolute indications for GBS prophylaxis regardless of delivery method:

  • Previous infant with invasive GBS disease
  • GBS bacteriuria during the current pregnancy 1, 2
  • Positive GBS screening culture in current pregnancy (unless cesarean before labor with intact membranes) 1

Clinical Implications

• Understanding this distinction helps avoid unnecessary antibiotic exposure
• Proper GBS screening remains important even with planned cesarean delivery
• The risk assessment should be updated if labor begins or membranes rupture before a scheduled cesarean

By following these evidence-based guidelines, healthcare providers can appropriately manage the risk of GBS transmission during cesarean deliveries while avoiding unnecessary antibiotic administration.