Pediatric Vital Signs by Age

Kids aren't small adults, and their vitals don't scale down from adult numbers. Read every value against an age band: neonate (0–28 days), infant (1–12 months), toddler (1–3 years), preschool (4–5 years), school-age (6–12 years) and adolescent (13–18 years). The band tells you what normal looks like for that child. A heart rate of 150 bpm is fast for a 10-year-old and within the awake range for a 3-month-old.

Why Kids Are Different

• Output depends on heart rate: Kids have small stroke volumes. Each beat moves little blood, so a slowing heart rate cuts cardiac output fast.
• Small oxygen reserve: Infants run out of oxygen fast. Apnea, airway obstruction or pneumonia can drop their SpO₂ quickly.
• Compensation hides shock: Tachycardia and vasoconstriction hold the blood pressure normal right up to sudden decompensation.
• Norms are not uniform: Published ranges disagree. Many guideline ranges are not evidence-based (see References).

1. Establish the age band: use the documented date of birth. If weight is needed and unknown, see Weight Estimation.
2. Measure in a calm state when possible: crying raises heart rate and respiratory rate. Count respiratory rate for a full 30–60 seconds in infants, because breathing is irregular.
3. Use the correct cuff: an undersized cuff reads falsely high and an oversized cuff reads falsely low.
4. Record the state with the number: awake, crying, sleeping or sedated.
5. Trend, do not stop at one set: repeat at set intervals and compare with the child's own baseline.

Heart rate is the most sensitive early vital sign in pediatrics. Pain, fear, fever, dehydration, blood loss: the heart rate climbs first for all of them. A slow heart rate in a child is the opposite of reassuring. It is almost always late, and it is ominous.

Bedside screening ranges like these are commonly cited from PALS. They are not AHA figures, because the 2025 AHA Part 8 text does not state age-band heart rate tables. The bands are approximate, and published centile charts (see References) draw some limits differently. Screen with them. Then look at the child.

Respiratory rate is the vital sign we guess at most often. In infants, count for a full 30–60 seconds. Crying can double the rate, so count while the child is calm when you can.

Blood pressure goes down last. It is the last vital sign to fall in pediatric shock. Kids hold it up with compensatory tachycardia and vasoconstriction until those mechanisms fail. Hypotension is a late finding.

Normal Systolic Blood Pressure

Between 11 and 18, a systolic of 90–120 mmHg is a rough screening band, and no sourced normal range backs it. Below 90 mmHg is the action threshold.

Phoenix Mean Arterial Pressure Thresholds

The 2024 Phoenix criteria score cardiovascular dysfunction on mean arterial pressure (MAP), not systolic. Measure it if you can. Calculating it works too: one-third systolic plus two-thirds diastolic. Age bands are not adjusted for prematurity.

• Phoenix sepsis (children under 18): suspected infection with a Phoenix Sepsis Score of 2 or more, summed across the respiratory, cardiovascular, coagulation and neurologic domains. A high lactate or low MAP alone does not establish sepsis without suspected infection.
• Phoenix septic shock: sepsis plus at least 1 cardiovascular point. Cardiovascular points: vasoactive medication (1 agent = 1 point; 2 or more agents = 2 points), lactate (5 to under 11 mmol/L = 1 point; 11 mmol/L or above = 2 points), and MAP in the reduced band (1 point) or the low band (2 points).
• Lactate: raised above 2 mmol/L (the Critical Care Transport reference range of 0.5–1.5 mmol/L is an adult value; use the laboratory's pediatric interval). Phoenix scores lactate at 5 mmol/L and at 11 mmol/L.

The 2025 AHA Part 8 text never states the 70 + (2 × age) hypotension formula. What it does give is a post-arrest target: keep systolic and mean arterial pressure above the 10th percentile for age (2025 AHA Guidelines for CPR and ECC, Part 8, COR 1, LOE B-NR). After arrest, it calls hypotension anything below the 5th percentile for age and sex.

Key Formulas

• Estimated normal systolic BP (1–10 years): 90 + (2 × age in years)
• Hypotension threshold (1–10 years): 70 + (2 × age in years)
• Hypotension threshold (over 10 years): below 90 mmHg
• MAP: one-third systolic + two-thirds diastolic

Nearly every emergency medication, fluid bolus and shock energy dose depends on weight. Measured weight always wins. No scale? Reach for a length-based tool such as the Broselow tape. An age formula is the last option.

Weight Estimation Formulas

Temperature

• Typical range: about 36.5–37.5 °C (97.7–99.5 °F) rectal
• Fever: ≥38.0 °C (100.4 °F) rectal
• Core reading: Rectal is the reference route in infants. Axillary and temporal readings run lower, so they can miss a fever.

Febrile Infants (8–60 Days)

The neonatal rule above covers 0–28 days. For well-appearing infants aged 8–60 days with fever ≥38.0 °C, the AAP 2021 guideline takes over, and it works in tiers by age. Infants 8–21 days usually get a lumbar puncture, blood and urine cultures, and admission for empiric antibiotics. Infants 22–28 days are risk-stratified with lab testing and inflammatory markers. Infants 29–60 days are risk-stratified with lab testing. Under 8 days, the guideline does not apply, and these infants are managed as highest risk. Older than 60 days, clinical judgment and local protocol decide.

Oxygen Saturation (SpO₂)

Most children sit at 95–100% SpO₂ at sea level. Newborns normally run low in the first minutes after birth. For resuscitation, use the NRP preductal targets below.

The 2025 table starts at 2 minutes. It gives no 1-minute target, so this page shows none. The targets come from the 2025 AHA Guidelines for CPR and ECC, Part 5.

• Pre-ductal vs. post-ductal: Pre-ductal is the right hand or wrist. Post-ductal is either foot. The 2025 Part 5 text puts the sensor on the right hand or wrist. A pre- to post-ductal difference above 3% triggers repeat testing and an evaluation for congenital heart disease. So does low SpO₂ after the newborn has stabilized. Follow local protocol.
• Sick child: The 2025 AHA Part 8 text gives 94–99% only after cardiac arrest. There it says weaning oxygen to that range may be reasonable (Part 8, COR 2b, LOE C-LD). It gives no SpO₂ target for sick children who have not arrested.
• Pulse oximetry limits: Poor perfusion, motion and a weak signal all reduce accuracy. Darker skin pigmentation can cause overestimation of SpO₂. Don't take comfort from a number that doesn't match how the child looks.

Quick Reference by Age

Pulled together from the bands above for a quick check. Weight here is an estimate. Measure it when you can.

Level of Consciousness

• AVPU (Alert, Voice, Pain, Unresponsive). Use it as a fast screen on any child, infants included.
• Pediatric Glasgow Coma Scale: A scored measure for documentation and trend. Infants and children who can't speak yet need age-appropriate verbal descriptors, not adult words. Use the same scale at every reassessment.
• Any new decline in response triggers a reassessment of airway, breathing, circulation and glucose.

• Age formulas are population estimates. They assume average growth. Body habitus gets ignored.
• Length-based tools depend on accurate measurement. Get it head to heel, with the child straight and still.
• Normal ranges are population norms. Read each child against the age band and the clinical picture.

Weight Source Hierarchy

1. Measured weight on a calibrated scale.
2. Recent caregiver-reported weight: expert opinion only. The cited study never tested it against a measured weight, so label it an estimate.
3. Habitus-adjusted length-based tool (PAWPER, Mercy). Availability varies by agency. Plenty of US EMS services don't stock them.
4. Length-based tape (Broselow), the practical default in most US EMS.
5. Age formula, the last option.

Accuracy by Method

All of these accuracy figures come from one ethnically diverse Australian emergency department cohort of 199 children. They are not universal. Still, the direction holds: length-based tools beat age formulas, and that supports the hierarchy above.

Neonates (0–28 Days)

• Ranges here are for term neonates. Preterm infants need a specialist's input.
• Expect low SpO₂ in the first minutes after birth. Use the NRP targets by minute.
• Any temperature ≥38.0 °C counts as an emergency until someone has evaluated it.

Infants (1–12 Months)

• Obligate nose breathers until about 4–6 months. Congestion can cause real distress.
• Weigh or length-measure before any weight-based decision.

Adolescents (13–18 Years)

• Hypotension threshold is below 90 mmHg, the same as for adults.
• Heart rate ranges approach adult values. Ask whether an adult protocol applies under local medical direction.

Children With Chronic Conditions

• Baseline vitals can differ with heart disease, chronic lung disease or a pacemaker. Compare against the documented baseline.
• Use the emergency information form if the family has one. It is where you'll find baseline values and equipment.

State or agency protocol commonly sets these roles.

• Equipment: carry age-appropriate BP cuffs, SpO₂ probes and a length-based tape.
• Restraint: use a size-appropriate restraint on the stretcher, never a caregiver's lap.
• Caregiver presence: keep the caregiver with the child when safe and possible.
• Heat loss: Infants lose heat fast. Keep them warm and recheck the temperature.
• Handoff: use a structured handoff (MIST or IMIST-AMBO) that includes serial vitals and the trend.