# What is my baby’s Kaiser sepsis risk?

Estimates a newborn’s risk of early-onset sepsis per 1,000 births from maternal factors with the Kaiser Permanente models (2024 update for universal GBS screening, or the original 2017 model), and after a well, equivocal, or ill clinical exam.

- Page: https://www.acalculator.org/health/kaiser-sepsis-calculator
- JSON spec: https://www.acalculator.org/health/kaiser-sepsis-calculator.json
- Version: b046f33692b6

## Default answer

Example with the default inputs (Kaiser model 2024: universal GBS screening, EOS incidence (per 1,000 births) 0.5 per 1,000, Gestational age: weeks 40, and days 0, Highest maternal temperature 98.6 °F, Rupture of membranes (hours) 10, Mother’s GBS status Negative, Antibiotics in labor None, or any given less than 2 hours before birth): The early-onset sepsis risk at birth is 0.29 per 1,000 births (0.1 per 1,000 if the baby appears well).

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| model | Kaiser model | Kaiser suggests the 2024 model where pregnant people have universal GBS screening, as in the US, and the original 2017 model where they do not. |
| inc | EOS incidence (per 1,000 births) | The rate of early-onset sepsis where the baby is born. 0.5 is the US national rate the tool names. |
| wk | Gestational age: weeks | Completed weeks of gestation at birth: 35 to 43 for the 2024 model, 34 to 43 for the 2017 model. |
| d | and days | Extra days past the completed weeks, 0 to 6. |
| t | Highest maternal temperature | The mother’s highest temperature in labor, before the birth. |
| rom | Rupture of membranes (hours) | Hours from when the waters broke to the birth, 0 to 240. |
| gbs | Mother’s GBS status | The group B streptococcus (GBS) test result in pregnancy. |
| abx | Antibiotics in labor | The type of antibiotics given to the mother in labor, and how long before the birth. In the 2024 model only ampicillin, penicillin, or cefazolin count as GBS prophylaxis. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| atBirth | Risk at birth | EOS risk per 1,000 births from the maternal factors, to 2 decimals. |
| well | If the baby appears well | EOS risk per 1,000 births after a well-appearing exam, to 2 decimals. |
| equivocal | If the exam is equivocal | EOS risk per 1,000 births after an equivocal exam, to 2 decimals. |
| ill | If the baby shows clinical illness | EOS risk per 1,000 births after an exam showing clinical illness, to 2 decimals. |

## Method

Risk at birth = 1 ÷ (1 + e^−x), x = intercept + b1 × temperature (°F) + b2 × GA + b3 × GA² + b4 × (ROM hours + 0.05)^0.2 + b5 × (GBS prophylaxis ≥ 2 h or broad-spectrum 2 to 3.9 h) + b6 × (broad-spectrum ≥ 4 h) + b7 × GBS positive + b8 × GBS unknown. 2024 model: 0.85194656, −7.72247124, 0.09842383, 0.86770862, −2.13142945, −2.33985917, 1.02265353, 1.13710111, exam LRs 0.36, 3.65, 14.5. 2017 model: 0.868, −6.9325, 0.0877, 1.2256, −1.0488, −1.1861, 0.5771, 0.0427, exam LRs 0.41, 5, 21.2. After the exam: odds × LR.

## Assumptions

- The 2024 model is for babies born at 35 weeks or later where GBS screening is universal; the 2017 model is for 34 weeks or later where it is not (Kaiser 2024 model FAQ).
- Risks are per 1,000 live births, rounded to 2 decimals, halves up.
- The page shows risk only. It does not show the care recommendations of the Kaiser tool.

## Worked examples

1. model = 2024, inc = 0.5, wk = 40, d = 0, t = 310.15, rom = 10, gbs = negative, abx = none gives atBirth = 0.29, well = 0.1, equivocal = 1.05, ill = 4.17. Source: Kaiser 2024 model FAQ: intercept 57.29929499 − ln[(0.9995 ÷ 0.0005) × (0.0002763 ÷ 0.9997237)] = 57.8926.
2. model = 2024, inc = 0.5, wk = 39, d = 3, t = 311.761111, rom = 20, gbs = positive, abx = gbs2 gives atBirth = 1.31, well = 0.47, equivocal = 4.76, ill = 18.63. Source: Kaiser 2024 model: 39 weeks 3 days, 101.5 °F, 20 hours, GBS positive, GBS prophylaxis: x = −6.6382, 1.3077 per 1,000.
3. model = 2024, inc = 0.3, wk = 37, d = 0, t = 311.038889, rom = 30, gbs = unknown, abx = broad4 gives atBirth = 0.44, well = 0.16, equivocal = 1.6, ill = 6.32. Source: Kaiser 2024 model, 0.3 per 1,000 (intercept 57.3816, the FAQ table gives 57.4): x = −7.7316, 0.4386 per 1,000.
4. model = 2017, inc = 0.5, wk = 40, d = 0, t = 310.15, rom = 10, gbs = negative, abx = none gives atBirth = 0.14, well = 0.06, equivocal = 0.69, ill = 2.93. Source: Puopolo 2011 model with the coefficients in Nguyen 2024 (Cureus) and the Kaiser 0.5 per 1,000 intercept 40.5656: 0.1384 per 1,000.
5. model = 2017, inc = 0.5, wk = 39, d = 3, t = 311.761111, rom = 20, gbs = positive, abx = gbs2 gives atBirth = 1.4, well = 0.57, equivocal = 6.95, ill = 28.84.
6. model = 2017, inc = 0.3, wk = 35, d = 0, t = 311.038889, rom = 30, gbs = unknown, abx = broad4 gives atBirth = 1.01, well = 0.41, equivocal = 5.01, ill = 20.89.
7. model = 2017, inc = 0.6, wk = 41, d = 2, t = 311.65, rom = 5, gbs = negative, abx = none gives atBirth = 1.73, well = 0.71, equivocal = 8.61, ill = 35.5.

## FAQ

### What is the Kaiser sepsis calculator?

It is a model from Kaiser Permanente Northern California that estimates the chance that a baby born at 34 or 35 weeks or later has early-onset sepsis, a bacterial blood infection in the first days of life. Puopolo and others (2011) built the risk at birth from maternal factors; Escobar and others (2014) added the baby’s condition. When Kaiser hospitals used it, antibiotic use in the first 24 hours fell from 5.0% to 2.6% of newborns (Kuzniewicz 2017).

### What goes into the risk at birth?

Five facts known at delivery: gestational age, the mother’s highest temperature in labor, how long the membranes (waters) were ruptured, the mother’s group B streptococcus (GBS) status, and the type and timing of antibiotics in labor. The model also needs the baseline rate of EOS where the baby is born.

### How does the baby’s exam change the risk?

The risk at birth is multiplied, as odds, by a likelihood ratio for the exam. The 2024 model uses the point estimates from the 2024 Kaiser model update: 0.36 if the baby appears well, 3.65 if the exam is equivocal, and 14.5 if the baby shows clinical illness. The original 2017 model used the upper 95% limits: 0.41, 5, and 21.2.

### Does this page say whether a baby needs antibiotics?

No. The Kaiser tool pairs each risk with care recommendations for clinicians. This page shows the risk numbers only. Decisions about tests, monitoring, and antibiotics belong to the baby’s care team.

### Which model should I use?

Kaiser suggests the 2024 model where pregnant people have universal group B streptococcus (GBS) screening, as in the US, and the original 2017 model where they do not. In the 2024 model an unknown GBS status triples the odds (odds ratio 3.11), because few mothers are untested where screening is universal; where screening is not universal, that would overstate the risk. The 2024 model is for 35 weeks or later; for a baby born at 34 weeks, use the 2017 model.

### What incidence should I choose?

The incidence is the baseline rate of early-onset sepsis per 1,000 live births at the hospital or in the region. The Kaiser tool names 0.3 per 1,000 for Kaiser Northern California and 0.5 per 1,000 as the US national rate.

## Sources

- Puopolo KM, Draper D, Wi S, et al. Estimating the probability of neonatal early-onset infection on the basis of maternal risk factors. Pediatrics. 2011;128(5):e1155-e1163. https://doi.org/10.1542/peds.2010-3464
- Escobar GJ, Puopolo KM, Wi S, et al. Stratification of risk of early-onset sepsis in newborns ≥34 weeks’ gestation. Pediatrics. 2014;133(1):30-36. https://doi.org/10.1542/peds.2013-1689
- Kuzniewicz MW, Puopolo KM, Fischer A, et al. A quantitative, risk-based approach to the management of neonatal early-onset sepsis. JAMA Pediatr. 2017;171(4):365-371. https://doi.org/10.1001/jamapediatrics.2016.4678
- Kuzniewicz MW, Escobar GJ, Forquer H, et al. Update to the Neonatal Early-Onset Sepsis Calculator utilizing a contemporary cohort. Pediatrics. 2024;154(4):e2023065267. https://doi.org/10.1542/peds.2023-065267
- Nguyen TT, Nguyen OTH, Duong MN, Giang LTP. Antibiotic management for early-onset sepsis in neonates with gestational ages of ≥34 weeks: the Kaiser sepsis calculator. Cureus. 2024;16(7):e63704, Appendix (model coefficients and likelihood ratios). https://doi.org/10.7759/cureus.63704
- Kaiser Permanente Division of Research. Neonatal Early-Onset Sepsis Calculator, original (2017) model, incidence options and intercepts. https://neonatalsepsiscalculator.kaiserpermanente.org/ (retrieved 2026-09-29)
- Kaiser Permanente Division of Research. Neonatal Early-Onset Sepsis Calculator, FAQ 2024 EOS Calculator Model Update (coefficients, intercept formula and table, likelihood ratios, which model to use). https://neonatalsepsiscalculator.kaiserpermanente.org/ModelUpdateFAQ.aspx (retrieved 2026-09-30)
- Kaiser Permanente Division of Research. Neonatal Early-Onset Sepsis Calculator, EMR implementation FAQ (the equation, the transformed rupture of membranes term, and the likelihood ratios). https://neonatalsepsiscalculator.kaiserpermanente.org/EmrFAQ.aspx (retrieved 2026-09-30)