Regarding the risk factors and epidemiology of early-onset neonatal sepsis (EOS), all of the following increase the risk of EOS in a term or preterm neonate EXCEPT:

Explanation

## Risk Factors for Early-Onset Neonatal Sepsis (EOS) **Key Point:** EOS (occurring within the first 72 hours of life) is acquired vertically from maternal flora during labor and delivery. Risk factors reflect conditions that increase vertical transmission or impair neonatal immune defenses. ### Major Risk Factors for EOS | Risk Factor | Mechanism | Impact on Risk | | --- | --- | --- | | **Maternal fever ≥38°C during labor** | Indicates possible chorioamnionitis or infection | Significantly increases EOS risk | | **Prolonged rupture of membranes (PROM) >18 hours** | Allows ascending infection from vaginal flora | Increases risk proportionally with duration | | **Prematurity (<37 weeks)** | Immature immune system, reduced opsonins, low IgG | Higher incidence of EOS; risk inversely proportional to GA | | **Maternal GBS colonization** | Vertical transmission of pathogenic organism | Risk present if **no** intrapartum antibiotic prophylaxis (IAP) | | **Maternal intra-amniotic infection** | Direct fetal exposure to pathogens | Very high risk | | **Low birth weight (<2500 g)** | Immature immunity | Increased EOS incidence | **High-Yield:** Maternal GBS colonization **with adequate intrapartum antibiotic prophylaxis (IAP)** is **NOT a risk factor** for EOS. IAP (typically penicillin G or ampicillin) reduces the risk of vertical GBS transmission by >90%. ### Intrapartum Antibiotic Prophylaxis (IAP) for GBS **Indications for IAP:** - Maternal GBS colonization (vaginal/rectal culture within 5 weeks of delivery). - Previous infant with GBS disease. - Maternal GBS bacteriuria during current pregnancy. - Unknown GBS status + risk factors (PROM >18 hours, fever ≥38°C, delivery <37 weeks). **Effect of IAP:** Reduces perinatal GBS transmission by >90%, making maternal GBS colonization a **non-risk factor** if IAP is given. **Clinical Pearl:** A neonate born to a GBS-colonized mother who received adequate IAP (≥2 doses of IV penicillin G or ampicillin, or 1 dose of cefazolin if penicillin-allergic) has minimal increased risk and may not require empirical antibiotics if asymptomatic and ≥35 weeks GA with ≥18 hours of maternal IAP. **Why Option 2 (Maternal GBS colonization WITH IAP) is WRONG:** - Intrapartum antibiotic prophylaxis reduces GBS transmission risk by >90%. - A GBS-colonized mother who received adequate IAP is **not** a risk factor for EOS. - The question specifies "with intrapartum antibiotic prophylaxis," which negates the risk.