Anyone who places his hand on the chest of a baby for the first time usually gets a fright: the beat sounds like a locomotive.
This is because the heart of the infant beats at a more rapid rate than that of an adult.
Whereas the heart rate of an adult is between 60-80 beats per minute, a newborn’s heart rate is between 120-160 bpm. Later on it is going to reduce gradually: at one month it does 100 – 150 beats per minute: at two years 85 – 125 beats per minute, at four years, 75 – 115 beats per minute, at six years 65 – 100 beats per minute and over six years 60-100 beats per minute.
If the hearts of chidren beat with greater frecuency it is because of its immaturity; their cells are smaller in size and they are not organized like those of the adult, because the capacity of the heart to contract is less.
Despite this lesser capacity, the oxygen needs are not less, but greater than the adult’s, because babies need more fuel per kilogram of weight.
This difficulty exceeds the baby’s heart increasing sensitivity to noepinephrine, a hormone and neurotransmitter, among other effects, it leads to an increase in heart rate.
Have you ever listened to a baby’s heart in the uterus? It is also impressive, even more so than that of a newborn baby. So the next time you hear the fast heartbeat of a baby, do not worry, do not be frightened, this is simply how it works.