Newborn · Infection
Early-Onset Neonatal Sepsis (EOS)
Bacterial infection in baby's first 72 hours: risk factors, Kaiser EOS calculator, signs to watch for, antibiotic treatment, recovery. NICE NG195 / AAP.
Last reviewed 2 June 2026
Early-onset sepsis (EOS) — Kaiser model
Neonatal sepsis risk per 1,000 live births
wk
°C
h
GBS status
Intrapartum antibiotics
Clinical exam at evaluation
Enter GA ≥ 34 weeks and clinical inputs to estimate EOS risk.
Educational tool only — not medical advice. Simplified categorical model. For clinical use, the original Kaiser Permanente Neonatal Sepsis Calculator (Kuzniewicz 2017) at neonatalsepsiscalculator.kaiserpermanente.org is the gold standard. AAP 2018/2019 endorses risk-based approaches for late-preterm and term neonates. Reduces unnecessary antibiotic exposure substantially vs categorical algorithms (Achten 2019 JAMA Pediatr — 60-70 % reduction in antibiotic exposure with similar outcomes).
What does this mean?
Early-onset neonatal sepsis (EOS, < 72 h of life) is rare — incidence ~0.4–1 per 1,000 live births in the GBS-prophylaxis era — but devastating when missed. The trade-off: traditional categorical algorithms (CDC 2010) recommended broad empirical antibiotics for any chorioamnionitis exposure or any GBS-prophylaxis gap, leading to 10–15 % of all newborns getting antibiotics when the true sepsis rate is < 1 %. The Kaiser Permanente EOS calculator (Kuzniewicz 2017) replaced this with a Bayesian model combining maternal risk factors AND the infant’s clinical exam — and reduced antibiotic exposure by 60–70 % with equivalent outcomes (Achten 2019 JAMA Pediatr meta- analysis). Less antibiotic exposure means less microbiome disruption, better breastfeeding establishment, shorter mother-baby separation, lower NICU costs. For clinical use, the original calculator (kaiserpermanente.org) remains the gold standard.
What is early-onset neonatal sepsis?
Bacterial infection in baby in first 72 hours. ~1 in 1,000 UK births. Can be life-threatening; early antibiotics save lives.
Common causes: Group B Strep (biggest), E. coli, Listeria.
Higher-risk babies
- Maternal GBS-positive.
- Prolonged ROM (>18h).
- Maternal fever in labour.
- Chorioamnionitis.
- Preterm.
Kaiser EOS calculator
Online tool for babies 34+ weeks. Inputs: gestational age, maternal temp, ROM duration, GBS status, antibiotics given, baby’s condition. Output: risk + suggested management.
Kuzniewicz NEJM 2017: reduces antibiotic exposure ~50% while maintaining safety. AAP supports; UK NICE NG195 uses risk-factor approach.
Signs of infection in newborn
- Fever >38°C or low temp <36°C.
- Poor feeding / vomiting.
- Lethargy / drowsiness.
- Irritability / inconsolable.
- Fast breathing / grunting.
- Pale / mottled skin.
- Jaundice in first 24h.
- Apnoea / blue tinge.
- Seizures (emergency).
Any signs: hospital review today.
Antibiotic treatment
- First-line: benzylpenicillin + gentamicin IV.
- Prophylactic (risk factors only): 36-48h pending culture.
- Confirmed sepsis: 5-7 days for blood culture-positive.
- Meningitis: 7-14 days.
Late-onset sepsis (after 72h)
Different bugs: coagulase-neg Staph (preterm), Staph aureus, Gram-negative. Risk: preterm in NICU, central lines, surgery. Hand hygiene crucial.
Prevention
- Hand hygiene — you + visitors.
- Avoid people with infections visiting in first weeks.
- Breastfeeding (transmits antibodies).
- GBS testing if relevant.
- Avoid unpasteurised foods in pregnancy (listeria).
- Up-to-date vaccines.
- Low threshold for medical review of unwell baby.
Going home — when to call
Call 111 / GP / A&E if:
- Fever (>38°C).
- Listless / hard to wake.
- Poor feeding.
- Respiratory issues.
- Non-blanching rash.
- Seizures.
- Any “just not right” feeling.
Different scenarios
Scenario 1: GBS-positive mum, baby born within 4h of antibiotics
Baby observed 24h on postnatal ward. No prophylactic antibiotics typically.
Scenario 2: Maternal fever 38.5 in labour, baby born vigorous
Empirical antibiotics 36-48h pending blood culture. NICU or postnatal ward depending on protocol.
Scenario 3: Preterm 33 weeks, respiratory distress
NICU. Antibiotics + CXR + cultures. Surfactant for RDS if needed.
Scenario 4: Day 4 baby at home, lethargic, fever
Late-onset suspected. A&E. IV antibiotics. Investigations including LP if meningitis suspected.
Scenario 5: Blood culture positive E. coli sepsis
7-day antibiotics. If LP positive, 14 days. Hearing test follow-up. Developmental review.
Care guidance — EOS
- Sign recognition at home + hospital.
- Empirical antibiotics within 1h of suspected sepsis.
- Blood culture before antibiotics if possible.
- Breastfeeding usually continued.
- Hand hygiene + visitor management.
- Hearing follow-up if severe.
- Low threshold for review — better safe than sorry.
Sources
- NICE NG195. Neonatal infection: antibiotics for prevention and treatment.
- Kuzniewicz MW, et al. A quantitative, risk-based approach to the management of neonatal early-onset sepsis. JAMA Pediatr 2017.
- AAP. Management of neonates born at ≥35 0/7 weeks gestation with suspected or proven early-onset bacterial sepsis.
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Frequently asked questions
What is early-onset neonatal sepsis (EOS)?
BACTERIAL INFECTION in baby in FIRST 72 HOURS of life. RARE (~1 in 1,000 live births in UK) but SERIOUS — can be life-threatening. COMMON CAUSES: GROUP B STREP (GBS, biggest cause); E. COLI; Listeria; other. BABIES at higher risk: maternal GBS-positive, prolonged ROM (>18h), maternal fever in labour, chorioamnionitis, preterm. SYMPTOMS: subtle — temperature instability, poor feeding, lethargy, respiratory distress, irritability. EARLY antibiotic treatment lifesaving.
What's the Kaiser EOS calculator?
ONLINE TOOL widely used to assess EARLY-ONSET SEPSIS risk in newborns 34+ weeks. INPUTS: gestational age, highest maternal temperature, ROM duration, maternal GBS status, broad-spectrum antibiotics given, baby's clinical condition. OUTPUT: estimated risk of EOS + suggested management. EVIDENCE: Kuzniewicz NEJM 2017 — reduces antibiotic exposure ~50% while maintaining safety. AAP supports use; UK varies (NICE NG195 categorical approach preferred by some).
When are antibiotics given to my newborn?
(1) CLINICAL signs of infection (any baby unwell) — antibiotics within 1 HOUR; (2) RISK FACTORS without clear illness — varies by protocol: NICE NG195 risk factors (e.g. mother GBS+ in this pregnancy without intrapartum antibiotics ≥4 hours before delivery; intrapartum antibiotics for suspected maternal infection; baby preterm); Kaiser calculator may guide selective treatment. STANDARD: BENZYLPENICILLIN + GENTAMICIN IV; usually 36-48 hours pending blood culture; longer if infection confirmed.
What signs of infection should I watch for?
BABY: (1) FEVER (>38°C) OR LOW TEMPERATURE (<36°C); (2) POOR FEEDING / vomiting; (3) LETHARGY / DROWSINESS / hard to wake; (4) IRRITABILITY / inconsolable; (5) FAST BREATHING / grunting; (6) PALE / mottled skin; (7) JAUNDICE in first 24 hours; (8) APNOEA (pauses in breathing); (9) BLUE TINGE; (10) SEIZURES (severe — emergency). ANY signs: hospital review TODAY. SEPSIS in newborns can deteriorate rapidly.
Will antibiotics affect my baby?
MOSTLY safe + necessary if needed. SHORT COURSE (48 hours pending culture): minimal effect. LONGER courses can affect: gut microbiome (rebalances over weeks-months); risk of Candida if very long; antibiotic-resistant bacteria emergence. PROBIOTICS sometimes given to preterm babies to support gut health. CONTINUE breastfeeding (helps gut flora). MOST babies tolerate antibiotics well.
What if blood culture is negative but baby was on antibiotics?
COMMON. ~5% of babies on antibiotic course have positive blood culture; 95% NEGATIVE. NEGATIVE culture by 36-48 hours: usually antibiotics stopped; baby observed; discharged when stable. CULTURES sometimes negative even when infection present (small bacterial load, antibiotic-treated mother). CLINICAL JUDGMENT: persistent symptoms warrant continued treatment. C-REACTIVE PROTEIN (CRP) + WHITE CELLS help guide.
What if my baby is on antibiotics in NICU?
BABY in NICU on antibiotics: usually IV. MONITORING: temperature, HR, RR, glucose, full neonatal observations. INVESTIGATIONS: blood cultures, FBC, CRP, blood gas, ?CXR if respiratory; LP (lumbar puncture) if meningitis suspected. PARENTS CAN VISIT freely (mostly). EXPRESS breast milk + feed when possible. BREASTFEEDING usually OK depending on baby's condition. STAY positive — most babies recover well.
How long does treatment take?
(1) PROPHYLACTIC (mother had risk factors, baby well): 36-48 hours pending blood culture negative; stop. (2) CONFIRMED INFECTION: 5-7 DAYS antibiotics for blood culture-positive sepsis; 7-14 DAYS if meningitis. (3) RECOVERY: variable. NICU stay depends on severity. POSITIVE FOLLOW-UP: hearing test (audiology) if any meningitis/severe sepsis.
Will my baby have lasting effects?
DEPENDS on severity + early treatment. MOST babies recover fully with prompt antibiotic treatment + supportive care. SEVERE sepsis with meningitis carries risk of: cerebral palsy; learning disability; deafness; visual problems; seizures; developmental delay. RARE in early-treated cases. FOLLOW-UP: hearing screen + developmental assessments. POSITIVE outlook for most.
What about late-onset neonatal sepsis?
LATE-ONSET = INFECTION AFTER 72 HOURS, up to ~28 days. DIFFERENT BUGS often: coagulase-negative Staph (preterm), Staph aureus, Gram-negative bacteria. RISK GROUPS: preterm babies in NICU; babies with central lines / surgery / breaches of skin. SYMPTOMS: similar to EOS but less acute often. TREATMENT: IV antibiotics; tailored to likely organisms; investigation of source. HAND HYGIENE in NICU + at home crucial for prevention.
How can I prevent neonatal sepsis?
GENERAL PRECAUTIONS: (1) HAND HYGIENE — yourself + visitors; (2) AVOID people with infections visiting in first weeks; (3) BREASTFEEDING (transmits protective antibodies); (4) ROUTINE PRENATAL CARE — GBS testing if relevant; (5) AVOID unpasteurised foods in pregnancy (listeria); (6) UP-TO-DATE VACCINES; (7) MIDWIFE / GP IF any concerns about baby. EARLY pregnancy contacts: maternal infection treatment essential.
Can my baby get sepsis after going home?
YES — possible especially first weeks. CALL 111 / GP / A&E if: fever (>38°C); listless / hard to wake; poor feeding; respiratory issues; rash (especially non-blanching); seizures; any 'just not right' feeling. NHS 111 always available; don't hesitate. BETTER to come in for nothing than miss serious illness. NEONATAL period (under 1 month): low threshold for medical review.
What if I refuse antibiotics for my newborn?
RARE but possible. INFORMED choice. CONSEQUENCES of declining when indicated: severe infection, brain damage, death possible. DISCUSS THOROUGHLY with neonatology team. SECOND OPINION available. SAFEGUARDING concerns if perceived risk to baby — court order possible in extreme cases (rare). MOST PARENTS who initially decline change mind once full risks explained.
What's chorioamnionitis?
INFECTION of the membranes around baby in pregnancy / labour. COMMON cause of EOS. SIGNS in mother: fever in labour, foul-smelling liquor (waters), uterine tenderness, raised CRP/WBC. ANTIBIOTICS during labour for mother. BABY MONITORED CLOSELY post-delivery; usually empirical antibiotics for 48 hours. RAISES risk of: EOS, preterm birth (if before term), maternal sepsis, postpartum endometritis. SEPSIS prevention starts in labour.
How does this relate to other calculators on BumpBites?
Companion: /calculators/gbs-prophylaxis for prevention; /calculators/maternal-sepsis (overlap); /calculators/baby-fever; /calculators/apgar-score; /calculators/neonatal-cooling; /calculators/newborn-bilirubin; /calculators/sarnat-hie.