At what age should an infant's heart rate fall within 110 to 160 beats per minute?

Infants typically have a higher heart rate compared to older children and adults due to their smaller size and higher metabolic demands. In general, the normal resting heart rate for infants ranges from 110 to 160 beats per minute. This range is established once the infant is about one month old, aligning with their physiological development during the early stages of life.

At birth, heart rates can be quite variable, and it is not uncommon for newborns to have heart rates above this range due to the stresses of birth and adjustment to extrauterine life. As they grow and develop in the first month after birth, their heart rate gradually stabilizes and falls within the typical range of 110 to 160 beats per minute. This important milestone reflects the maturation of their cardiovascular system.

By the time an infant reaches six months or one year, their heart rate generally continues to decrease as their body grows and their cardiovascular fitness develops, often falling to lower resting heart rates. Therefore, one month is the correct age at which to expect the heart rate to consistently fall within this specific range.