The birth of a new baby is greeted by many questions from
parents, relatives and friends. "Is the baby okay?" "Does the baby have all
its fingers and toes?" The next most common questions are about the infant’s
size - "how much did the baby weigh and what is the length?" These important
values are then carefully recorded in the infant’s "baby book," written on
birth announcements, and given out to grandparents, relatives and friends.
Parents really have the right idea here. These measurements
will become a good indicator of the baby’s overall health, especially during the
first three years. Physicians too are well aware of this close relationship. Infants who
are well nourished nutritionally, receive emotional bonding from their parents, and have
not developed a chronic medical problem will grow following a regular pattern.
Pediatricians and family physicians use a growth chart to
keep track of a child’s progress. As all of us realize, there is a wide variation in
the height and weight of "normal" children. Growth charts were developed from
information obtained by measuring and weighing thousands of children. From these numbers
the national average for weight and height for each age and sex were established and
plotted forming a curved line. This became the 50th percentile curve, meaning
in a sample of 1,000 boys or girls, 500 would be above the curve and 500 would be below.
Then other curves were established representing the 10th, 25th, 75th,
and 90th percentiles. By definition, 100 out of one thousand normal children
will be at the 10th percentile. Another way of looking at it is that a child
whose height fell on the 10th percentile would be taller than 100 and shorter
than 900 children of the same age and sex. Four separate charts are published by the
National Center for Health Statistics: boys, birth to 36 months and 3 to 18 years of age,
and girls, birth to 36 months, and 3 to 18 years of age. Growth charts are adjusted for
babies born prematurely and babies who are small-for-dates at birth.
Parents often focus their attention on where a child’s
growth is plotted on the chart. This may be particularly concerning to a parent if the
measurement falls below the 50th percentile. Does this mean that their daughter
will not make the dean’s list or their son will be too short to play basketball?
Absolutely not! As long as the child is consistently in the normal range (between the 10th
and 90th percentile) and stays in that range on multiple well child visits,
everything is fine. Physicians become concerned when the child repeatedly falls
below the lower limits for weight or height, or above the upper limits for weight. What
is important is that the child gets on a steady percentile line
and stays there. For example, a physician might worry if at a six-month-old baby was
in the 75th percentile and at nine months was in the 25th percentile
and then at 16 months was below the 10th percentile.
Another measurement performed during well checkups is the
head circumference. Like height and weight, head circumference is carefully recorded and
plotted on its own chart. Pediatricians become concerned when the head is growing too
slowly or too quickly on repeated measurements. This measurement is also adjusted
for babies born prematurely.
It is important to emphasize again that parents not focus
their attention on an isolated entry in their youngster’s growth chart. Measurement
errors do occur - the squirming infant on a baby scale may be difficult to weigh, a
toddler recovering from a bout of diarrhea may seem to have dropped weight percentiles, or
the slouching adolescent being measured during a sports physical. The growth trends over
successive visits are more accurate and provide parents and physicians with important
information about a child’s health.
The growth charts on our site are the latest pediatric growth
charts issued by the Center for Disease Control (May, 2000). These updated charts are more
representative of the U.S. Population and will be used by pediatricians, nurses, and
nutritionists to monitor children’s growth. To learn more about the new pediatric growth charts, click here.
Special Growth Charts
Children Born Prematurely
Body Mass Index