What is the normal respiratory rate for infants?

Normal Respiratory Rate for Infants

The normal respiratory rate for infants under 1 year of age ranges from 20 to 60 breaths per minute, with rates below 20 breaths per minute considered bradypnea requiring immediate medical attention. 1

Age-Specific Respiratory Rates

• In hospitalized children, the 50th percentile for respiratory rate decreases from 41 breaths per minute at 0-3 months of age to 31 breaths per minute at 12-18 months of age 2
• Respiratory rate in otherwise healthy children changes considerably over the first year of life 2
• For newborns, the American Academy of Pediatrics defines tachypnea as a respiratory rate greater than 60 breaths per minute 3
• The World Health Organization defines tachypnea in children 12-59 months as ≥40 breaths per minute 4

Factors Affecting Respiratory Rate Measurement

• Respiratory rate is significantly affected by the infant's state:

  • Awake and content infants: mean of 61 breaths per minute 5
  • Sleeping infants: mean of 42 breaths per minute (significantly lower than when awake) 5
  • Crying infants: mean of 51 breaths per minute 5

• Measurement technique matters:

  • Counting respiratory rate over the course of 1 minute is more accurate than shorter observations 2
  • Respiratory rate measured with a stethoscope is systematically higher than that obtained by observation (mean difference 2.6 breaths/minute in awake and 1.8 breaths/minute in asleep children) 6
  • 15-second breath counts extrapolated to a minute yield significantly lower rates than full 60-second counts 7

Clinical Significance

• Bradypnea (respiratory rate <20 breaths per minute) in infants under 1 year should be considered an alarm sign requiring immediate medical attention 1, 4
• Tachypnea (≥60 breaths per minute) has been associated with increased risk of severe disease in some studies 2
• The presence of a normal respiratory rate suggests that risk of significant viral or bacterial lower respiratory tract infection or pneumonia in an infant is low (negative likelihood ratio approximately 0.5) 2
• The presence of tachypnea alone does not distinguish between viral and bacterial disease 2

Age Trends

• There is a decline in respiratory rate from birth to early adolescence, with the steepest fall apparent in infants under 2 years of age 8
• Median respiratory rate decreases from 44 breaths per minute at birth to 26 breaths per minute at 2 years 8
• Heart rate shows a small peak at age 1 month (increasing from 127 beats per minute at birth to 145 beats per minute at about 1 month) before decreasing to 113 beats per minute by 2 years of age 8

Measurement Best Practices

• Avoid measuring respiratory rate when the child is crying or agitated, as this can distort respiratory patterns 4
• Remember that respiratory signs can be subtle, infrequent, and variably present, even during a single patient encounter 4
• For the most accurate measurement, count breaths for a full 60 seconds rather than shorter periods 2, 7