Daily length measurements (in centimeters) versus age (in years) for a male infant showing growth spurts.
Despite much anecdotal evidence and the convictions of many parents, biologists have not generally recognized the reality of short, sharp growth spurts on the order of 1 centimeter in a single 24hour period. Rather, the consensus has been that child growth was divided into three stages (infancy, childhood, adolescence), each characterized by different, but steady rates of growth. This conclusion was based upon annual and quarterly length measurements. However, when children are measured more often (weekly or daily), the growth curve is seen to be step-like rather than smooth, as in the accompanying illustration. Indeed, the mean amplitude of the growth spurts was found to be about 1 centimeter; and the duration of the spurts, about one day. These spurts punctuated long intervals of no growth. In infants, for example, 90-95% of their development is growth-free!
(Lampl, M., et al; "Saltation and Stasis: A Model of Human Growth," Science, 258:801, 1992.)