pregnancy, and ultrasound assessments of fetal size became a regular aspect of
obstetric care. Only more recently has the size and early growth of the fetus become
appreciated for its predictability of health and well-being for offspring themselves,
not only in the moment, but also later in life as a reflection of the quality with which
the“building blocks”of the body were established (Barker 2007 ).
Concerns about the normality of growth are rare for the majority of children
living in developed countries, who are regularly monitored by pediatricians, school
nurses, and community health workers. Notions about proper growth have been
established principally on the basis of comparative size among similarly aged
individuals. This begins in the prenatal exam and continues in delivery rooms when
—merely moments after birth—an infant’s weight, length, and head circumference
are measured and compared to the averages described by infant growth charts.
Infants are subsequently measured at pediatric well-baby visits to provide a window
into their developmental progress and nutritional well-being. The practice of yearly
measurements follows throughout childhood and into adolescence, when the
coincidence of more rapid annual growth and the emergence of secondary sexual
characteristics initiate thefinal phase of childhood and the onset of adulthood. The
individual then passes from the watchful eye of the pediatrician to that of the
internist as the skeletal growth trajectory attenuates, and the size of the body
becomes a health concern for its composition alone.
For many people, growth is a consciously uneventful biological journey across
development. For others, the tempo of growth brings about periods of angst for the
relatively shortest, tallest, or unusually under- or over-developed individual in the
school yard. It is appreciated that the remarkable individual variability in size and
maturational level evident among children of similar ages reflects interplay among
genetic and environmental factors. The common scientific summary of this process
appears as a graph of increasing size across time with the age-based differences in
size captured by descriptive statistics in percentiles from small to tall (Fig.4.1). The
graphs imply a simple, steady paced trajectory of increasing size across time, albeit
with more rapid accrual in infancy and adolescence by comparison with childhood.
Individuals do not, however, actually grow according to such a steady clock. To the
contrary, children grow by leaps and bounds after intervals of quiescence: Growth
is a saltatory biological process with episodic accruals in length, height, and head
circumference punctuating stases in growing tissue biology (Lampl et al. 1992 ;
Lampl and Johnson2011b) (Fig.4.2). Both individual variability in growth tempo
across similar time intervals, and developmental age-based growth rate differences
(rapid fetal, infant, and adolescent growth rates compared to those during child-
hood), reflect variability in the timing and frequency, as well as amount of growth,
or the amplitude, of discrete growth saltations (Lampl et al. 1998 ).
Many children experience these episodic saltatory growth events as searing pains
in the shins at night, and some sage grandparents quell their concerns by noting that
these are merely“growing pains” that will pass (Evans 2008 ). While long a part of
parental lore, growth spurts have only recently been characterized scientifically and
remain to be understood mechanistically. In reality, growing is not merely back-
ground noise to daily life, but occurs by discrete episodes that are lived experiences.
48 M. Lampl et al.