What is the normal range of blood pressure (BP) readings in infants?

Normal Blood Pressure Ranges in Infants

The normal blood pressure range for infants varies by age, with systolic/diastolic values starting at approximately 78/47 mmHg at 2-3 weeks of age and increasing to 95/60 mmHg by 1-5 months of age, with minimal change until 2 years of age.

Normal BP Values in Infants by Age

Neonatal Period (0-28 days)

• Healthy term neonates (12-36 hours of life): 82.0 ± 7.5 mmHg systolic and 41.7 ± 5.8 mmHg diastolic 1
• 2-3 weeks of age: 78/47 mmHg (mean 59 mmHg) 2

Early Infancy

• 1-5 months: 95/60 mmHg (mean 74 mmHg) 2
• 6-12 months: No significant increase from the 1-5 month values 2

Late Infancy to Early Childhood

• 1-2 years: 96/56 mmHg (mean 71 mmHg) 2
• After 2 years, systolic and mean pressures begin to increase at an average annual rate of 2 mmHg for systolic pressure and 1 mmHg for mean pressure 2

Important Considerations for BP Measurement in Infants

Proper Technique

• Cuff size: Use a cuff with bladder width that is 40-50% of the arm circumference 2
• Position: Measure BP with the infant calm and quiet when possible
• Arm selection: The right arm is generally preferred for consistency and comparison with reference tables 3
• Method: Oscillometric method is most commonly used in clinical settings and has a high success rate in infants 2

Interpretation Guidelines

• No significant differences in BP values between boys and girls or among ethnic groups in the first 5 years of life 2
• Diastolic pressure remains relatively stable from 1 month to 5 years of age 2
• Heart rate decreases with age, from approximately 153 beats per minute at 2-3 weeks to 97 beats per minute at 5 years 2

Defining Elevated BP in Infants

• For neonates, systolic BP ≥95 mmHg and diastolic BP ≥52 mmHg may be considered elevated 1
• For infants 1-12 months, flush method values should not exceed 100 mmHg; Doppler systolic levels should not exceed 113 mmHg 4

Clinical Implications

Measurement Challenges

• BP measurement in infants can be challenging due to their small arm size and activity level
• Multiple readings (ideally three) should be obtained when possible to ensure accuracy 2
• The oscillometric method has been shown to be successful in obtaining BP measurements in 87% of infants less than 3 years of age 2

Monitoring Recommendations

• While specific screening recommendations for infants under 3 years are not as clearly defined as for older children, BP should be measured when an oscillometric device is available 2
• BP measurement is particularly important in infants with risk factors for cardiovascular or renal disease

Pitfalls to Avoid

• Using an inappropriately sized cuff can lead to inaccurate readings
• Failing to account for the infant's state (crying, agitated) which can temporarily elevate BP
• Comparing values obtained by different measurement methods without considering methodological differences
• Interpreting isolated elevated readings as hypertension without confirmation

Remember that BP values in infants should be interpreted in the context of the infant's clinical condition, as the complex physiology in newborns makes it difficult to identify a single "normal" BP for a specific infant at a specific time 5.