While unappreciated as growth-driven, behavioral aberrations such as outbursts of
fussiness and irritability accompany these growth events, impinging on individual
and family well-being. Parents are well aware of these types of eruptions, with
full-blown tantrums emerging suddenly and confounding explanation. The fact that
these types of behaviors are not merely randomflare-ups of poorly behaving infants
and children, but instead may represent psychophysiological manifestations of
growth biology, is important to consider. Growth as a lived experience is a largely
underappreciated phenomenon. This reflects the lack of documentation detailing
saltatory growth patterns.
Understanding the different constructs by which growth has traditionally been
conceptualized and monitored provides a framework to understand how growth is
“seen”scientifically. Fundamental to this has been a traditional methodological
focus on thesizeof children instead of the paths by which size is accrued, or the
actualgrowingthat occurs assize changeswithin individuals. In contrast, serial
Fig. 4.1 Growth charts depict size for age by percentile distributions, with size on the vertical
axis and age on the horizontal axis. These are derived from body size measurements taken on
individuals grouped by similar age and sex. Historically, these data have been collected both
cross-sectionally and longitudinally, with the latter being the ideal method. Descriptive statistics
are used to characterize the nature of the sample into 5th, 10th, 25th, 50th, 75th, 90th, and 95th
percentile categories of size for age, for example, and curve-fitting procedures then align each of
the percentiles across age to create a continuous graphic. The general shape of the curve reflects
the fact that size increases more rapidly during infancy and adolescence by comparison with
childhood. Children below the 10th and 5th percentiles, relatively smaller than their peers, are
often identified for further attention for“undergrowth”and those above the 95th percentile may
draw attention for“overgrowth”
4 The Lived Experience of Growing 49