Growth, Development and Health Supervision · 9 min read
Growth Assessment, Growth Patterns and Obesity
The PNCB outline places about 30% of scored items in Health Maintenance and Promotion and about 35% in Assessment and Diagnosis, and this material feeds both domains. Expect items that hand you a growth chart description and ask what it means, items that give a milestone set and ask whether the child is on track, items that ask which screening tool belongs at a given visit, and items that ask what the NP should tell the parent next. Management items test what to do with a positive screen (refer, repeat, counsel), and the right answer is often "refer now while continuing surveillance" rather than "wait and recheck."
This chapter covers accurate measurement, the choice of growth chart, expected growth velocity at each age, short stature patterns, faltering growth and the AAP approach to overweight and obesity.
Measurement and Growth Charts
Growth is the single best indicator of a child's overall health. One measurement shows size; serial measurements show velocity, and velocity is what reveals disease.
Which Growth Chart to Use
| Age or group | Chart | Notes |
|---|---|---|
| Birth to 2 years | WHO growth standards | Describe how healthy breastfed infants should grow |
| 2 to 20 years | CDC growth charts | Standing height; BMI-for-age |
| Severe obesity | CDC extended BMI-for-age charts | Express BMI as a percent of the 95th percentile |
| Preterm infants | Preterm (Fenton-type) chart, then WHO chart using corrected age | Correct for prematurity until 24 months |
| Down syndrome and some other conditions | Condition-specific charts used alongside standard charts | Interpret against both |
On WHO charts, the 2nd and 98th percentiles (about ±2 standard deviations) mark the outer limits of normal, so a weight-for-length below the 2nd percentile or above the 98th percentile needs attention. A weight-for-length at or above the 98th percentile in an infant signals excess weight gain.
Exam Tip: When a stem gives a 15-month-old's BMI, it is a distractor. Under 2 years the correct parameter is weight-for-length on the WHO chart.
Expected Growth by Age
Normal Growth Benchmarks
| Parameter | Expected pattern |
|---|---|
| Newborn weight loss | Up to about 7-10% of birth weight; birth weight regained by 10-14 days |
| Weight gain 0-3 months | About 20-30 g/day (roughly 1 oz/day) |
| Weight gain 3-6 months | About 15-20 g/day |
| Weight gain 6-12 months | About 10-15 g/day |
| Weight milestones | Doubles birth weight by about 4-6 months; triples by 12 months |
| Length, first year | Increases about 50% (about 25 cm) |
| Length, second year | About 12 cm |
| Height, age 3 to puberty | About 5-6 cm per year |
| Head circumference | About 2 cm/month for the first 3 months, 1 cm/month at 4-6 months, 0.5 cm/month at 6-12 months; about 12 cm total in the first year |
| Fontanels | Posterior closes by about 1-2 months; anterior closes by about 9-18 months |
Growth velocity slows sharply in the second year. A toddler whose appetite seems to "fall off a cliff" after the first birthday is usually showing normal physiology, and reassurance with a plotted chart is the right response.
Many healthy infants shift percentiles during the first 2 years as they move toward their genetic potential. Large babies of small parents may drift down, and small babies of tall parents may drift up. Crossing percentiles in this period needs a careful look at intake, family heights and overall health, but it is not automatically disease.
Mid-parental (target) height estimates genetic potential. For boys, add the father's and mother's heights, add 13 cm and divide by 2; for girls, add the two heights, subtract 13 cm and divide by 2. Most children land within about 8.5 cm of this target.
Short Stature Patterns
| Pattern | Growth velocity | Bone age | Clues |
|---|---|---|---|
| Familial (genetic) short stature | Normal | Equal to chronological age | Short parents; normal puberty timing |
| Constitutional growth delay | Normal after early deceleration | Delayed | Late puberty, family history of "late bloomers," catches up later |
| Pathologic (endocrine, systemic) | Decreased; crossing percentiles downward | Usually delayed | Hypothyroidism, growth hormone deficiency, celiac disease, IBD, Turner syndrome |
Clinical Pearl: Weight drops before height in nutritional and systemic disease (celiac, IBD, poor intake), so the child is thin and short. In endocrine causes such as hypothyroidism, growth hormone deficiency or Cushing syndrome, height slows while weight is preserved, so the child is short and heavy. A child with obesity who is tall for age usually has exogenous (lifestyle) obesity.
Common Trap: Ordering growth hormone testing for a short child growing steadily along the 3rd percentile with short parents and a bone age equal to chronological age. This is familial short stature; the next step is reassurance and continued monitoring. Any girl with unexplained short stature, however, needs a karyotype to exclude Turner syndrome.
Faltering Growth (Failure to Thrive)
Faltering growth is inadequate weight gain for age. Common definitions are weight-for-age or weight-for-length below the 2nd percentile on the WHO chart, or a fall across two or more major percentile lines. It is a sign, not a diagnosis.
Most cases are due to inadequate caloric intake: incorrect formula preparation, poor breastfeeding transfer, excessive juice, restrictive diets, feeding difficulties, food insecurity, caregiver depression or neglect. Fewer cases result from inadequate absorption (celiac disease, cystic fibrosis, cow's milk protein allergy) or increased requirements (congenital heart disease, chronic lung disease, hyperthyroidism, chronic infection).
Assessment priorities:
Detailed feeding history: what, how much, how often, how prepared, who feeds, mealtime behaviors. A 3-day diet record is useful.
Observe a feeding in clinic, including breastfeeding latch or bottle technique.
Psychosocial history: caregiver depression, food insecurity (Hunger Vital Sign), housing, substance use, intimate partner violence.
Physical exam for dysmorphic features, signs of systemic disease, and signs of neglect or abuse.
Limited laboratory screen guided by history: CBC, comprehensive metabolic panel, urinalysis, lead level when indicated, TSH, and celiac serology (tTG-IgA with total IgA) if the child eats gluten. Broad laboratory panels without clues have very low yield.
Management is primarily nutritional: increase caloric density (for example, concentrating formula under supervision or adding fats to table foods), structure meals and snacks, limit juice and milk grazing, address caregiver stressors, enroll in WIC and other supports, and recheck weight frequently (often every 1-2 weeks at first). Catch-up growth often needs about 1.5 times the usual caloric intake for age. Involve a dietitian and, when needed, feeding therapy.
Hospitalize for severe malnutrition, dehydration or medical instability, suspected abuse or neglect, or failure of carefully monitored outpatient management.
Case Snapshot: A 7-month-old exclusively breastfed girl has fallen from the 50th to the 5th percentile for weight since 4 months, with length and head circumference preserved. Her mother returned to work, pumps twice daily and reports the infant takes "a few ounces" by bottle from a grandparent. Exam is normal. The correct decision is a detailed feeding assessment and nutritional plan (pumping frequency, volumes, introduction of energy-dense complementary foods) with weight checks in 1-2 weeks, because the pattern (weight down first, length and head preserved) and history point to inadequate intake rather than organic disease.
Overweight and Obesity
Childhood obesity is common and tracks into adulthood. The AAP clinical practice guideline treats obesity as a chronic disease and rejects "watchful waiting."
BMI-for-Age Categories (2 Years and Older)
| Category | Definition |
|---|---|
| Underweight | BMI below the 5th percentile |
| Healthy weight | 5th to below the 85th percentile |
| Overweight | 85th to below the 95th percentile |
| Obesity (class 1) | 95th percentile or higher |
| Severe obesity class 2 | 120% to below 140% of the 95th percentile (or BMI ≥35) |
| Severe obesity class 3 | 140% or more of the 95th percentile (or BMI ≥40) |
Evaluation includes family history (obesity, type 2 diabetes, early cardiovascular disease, dyslipidemia), diet and activity history, sleep and snoring, mood and disordered eating, medications that promote weight gain (atypical antipsychotics, glucocorticoids, some antiseizure drugs) and an exam for blood pressure, acanthosis nigricans, striae, hepatomegaly, tonsillar hypertrophy, gait and hip pain (slipped capital femoral epiphysis, Blount disease) and dysmorphic features. Genetic syndromes such as Prader-Willi syndrome usually present with developmental delay, short stature or hyperphagia beginning early in childhood.
Comorbidity screening per the AAP guideline:
Age 10 and older with obesity: lipid panel, glucose metabolism (A1C, fasting plasma glucose or oral glucose tolerance test) and ALT for metabolic dysfunction-associated steatotic liver disease.
Age 10 and older with overweight plus risk factors (family history, signs of insulin resistance): consider the same tests.
Ages 2-9 with obesity: a lipid panel may be considered.
Screen for hypertension, obstructive sleep apnea, depression and disordered eating at every opportunity.
Treatment tiers:
Motivational interviewing in every visit, using nonstigmatizing language ("a weight that is healthy for you," not "obese child").
Key Takeaways
Use WHO charts from birth to 2 years (weight-for-length, not BMI) and CDC charts from 2 to 20 years (BMI-for-age).
Infants regain birth weight by 10-14 days, double it by about 4-6 months and triple it by 12 months; length increases about 50% in year one.
Familial short stature has normal velocity and normal bone age; constitutional delay has normal velocity and delayed bone age; falling velocity suggests pathology.
Faltering growth is usually inadequate intake; take a careful feeding and psychosocial history before ordering broad labs.
Obesity is BMI ≥95th percentile; severe obesity is ≥120% of the 95th percentile. Treat actively: IHBLT for all, medication from 12, surgical referral from 13 with severe obesity.
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