Average pulse-rate of children

The second important factor to which our data contribute is the average pulse-rate of children of the same age, both as to its absolute value and as to the deviation therefrom which can be expected for children in repose. With boys, one of the most extensive series numerically that we have for any age represented is that for the group 7 months old, in which the basal pulse-rate for the 13 boys ranged from 107 to 127. The average for this group is found to be 117. It is clear, therefore, that it is only with a great deal of reserve that one may speak of the pulse-rate of a boy of 7 months as being 117. Even wider differences are observed with the 4 boys of 20 months, the lowest being 92 and the highest 127, with an average of 111.

From the foregoing discussion of the considerable variation to be found with an individual in the earlier years, one would naturally expect similar large differences between groups of older children of the same age. Thus, for the 7 boys 7 years of age, the lowest is 74 and the highest 99. With the 5 boys 9 years of age, the lowest record is 71 and the highest 86, while the 9 boys 11 years of age show a maximum difference in their basal pulse-rates of 22 beats.

With girls, one of the largest groups at the earlier ages is that for 6 months, but the pulse-rates for these 8 girls range only from 118 to 132, with an average of 124. This approach to uniformity, which is much closer than that noted for boys, does not by any means hold for all ages, since at 16 and 18 months differences amounting to 40 and 32 beats, respectively, are observed. Bearing in mind the irregularities seen in the careful examination of the data for these several age-groups, we may average these pulse data and attempt to portray the general trend of the minimum or basal pulse-rate of boys and girls from birth to 13 years of age. In so doing we have left out of the averaging all age-ranges represented by less than three individuals.

The average values shown for boys indicate a reasonably constant pulse-rate for the first 14 months of life, ranging from 113 to 125, if we exclude the first 5 days, and from 105 to 125 if these earlier values are included. Thereafter the picture is a gradual decrease, persisting throughout the second and much of the third year. The data between 3 and 6 years are lacking. During this period there has been a very considerable fall, the tendency to a decrease continuing subsequent to 7 years. The lowest value is 69 at the age of 12 years. With girls, the averages show that after the first 11 days there is a distinct tendency for a rise in pulse-rate, the return to the rate of the first week not taking place until shortly after the end of the first year. There is then a continued decrease, the lowest record being 74 at the age of 7 years.