Respiratory rates of Indian infants under 2 months of age

There are few data from developing countries, including India, on the normal range of the respiratory rate (RR) recorded by observation. To determine the normal range of RR in infants up to 8 weeks of age and to define tachypnoea, we studied 100 healthy infants, 50 of normal birthweight and 50 of low birthweight) at 1, 2, 4, 6 and 8 weeks of age. The RR was recorded by observation and auscultation simultaneously for 60 seconds on each visit when the baby was either asleep or awake and content. The median RRs ranged between 42 and 43 breaths/min in infants of normal birthweight and 40 and 44 breaths/min. in low birthweight infants. Inter-age variability up to 8 weeks of age was very slight and statistically insignificant. Only 2-10% of the infants at any given age had a RR > or = 60/min. At all ages, RR by observation was higher than that by auscultation (p < 0.001). Neither birthweight nor gender significantly influenced the RR. When awake, infants had significantly higher RRs than when asleep. The RR extrapolated from a 15-second breath count was significantly lower (p < 0.05-0.01), whereas results from 30-second counts were similar to 60-second counts. Our data endorse the use of a RR > or = 60 breaths/min. counted for 1 minute as a cut-off to define tachypnoea in infants < 2 months of age.