Paediatrics chapters
Growth: anthropometry, growth charts, red flags and Tanner staging
How children grow, how to measure and plot weight, length and head size, what the centile lines mean, which growth patterns are worrying, and how puberty is staged.
- Weight is the most sensitive single index of growth; height reflects long-term (chronic) nutrition and head circumference reflects brain growth.
- Plot serial measurements on a centile chart: a child following a line is usually normal, while crossing two major centile lines or falling below the 3rd centile needs assessment.
- Short stature with normal growth velocity is usually familial or constitutional; slow velocity (under about 5 cm a year) suggests disease such as hypothyroidism or GH deficiency.
On this page
Overview
Growth is the increase in body size (measured in kilograms and centimetres). Development is the gain of skills and function. The two are assessed together at every child visit.
Growth is fastest in fetal life, in the first year and again at puberty. A single measurement only tells you the child's size today. Serial measurements plotted on a chart tell you whether the child is growing normally, and the rate of growth matters more than the absolute size.
Anthropometric measurements
Weight
- Most sensitive and most used index of growth and nutrition; it changes before other measures.
- Newborns lose up to 10% of birth weight in the first days (meconium, urine, fluid shift, low intake) and regain it by about day 10.
- Weigh infants naked on calibrated scales; older children in underwear.
| Age | Average weight (Akbar's rule of 7) |
|---|---|
| Birth | 3.5 kg (7 lb) |
| 6 months | 7.5 kg |
| 1 year | 10 kg |
| 2 years | 12 kg |
| 3.5 years | 15 kg |
| 7 years | 22 kg |
| 10 years | 32.5 kg |
Rate of gain: about 200 g a week in the first months, then about 150 g a week up to 1 year (Akbar); Nelson gives 20-30 g a day for the first 3-4 months, then 15-20 g a day. After that about 2.5 kg in the second year and about 2 kg a year until puberty.
Birth weight is doubled by about 5 months (Akbar gives 5-6 months), tripled at 1 year and quadrupled at 2 years.
Weight estimation formulas (Weech):
| Age | Weight (kg) |
|---|---|
| 3-12 months | (age in months + 9) ÷ 2 |
| 1-6 years | (age in years × 2) + 8 |
| 7-12 years | (age in years × 7 − 5) ÷ 2 |
A 3-year-old: (3 × 2) + 8 = 14 kg
A 9-month-old: (9 + 9) ÷ 2 = 9 kg
An 8-year-old: (8 × 7 − 5) ÷ 2 = 51 ÷ 2 = 25.5 kg
Length and height
- Measure length lying down (infantometer, two people) under 2 years; standing height (stadiometer, no shoes, heels and knees against the frame) from 2 years.
- Birth length about 50 cm; adds 25 cm in the first year (75 cm at 1 year), about 12 cm in the second year (85-87 cm at 2 years).
- About 95 cm at 3 years and 100 cm at 4 years; birth length doubles by about 4 years.
- Then about 5-6 cm a year until the pubertal spurt.
- Adult height is roughly twice the height at 2 years.
- Formula from 2 to 12 years: height (cm) = (age in years × 6) + 77.
Height reflects past (chronic) nutrition; it falls behind only with long illness. Weight reflects current status and drops even in acute illness. A child can lose weight but cannot lose height.
Head circumference (occipitofrontal)
- Use a non-stretch tape over the most prominent part of the occiput and the forehead; take three readings and record the largest.
- Measure at every visit in the first 2 years.
| Age | Head circumference |
|---|---|
| Birth | 34-35 cm |
| 3 months | 41 cm |
| 6 months | 44 cm |
| 1 year | 47 cm |
| 2 years | 49 cm |
| 5 years | 51 cm |
- Brain growth is rapid in infancy, slows after 1 year and adds little after 5 years.
- At birth the head is larger than the chest. They become equal between 6 months and 1 year (Park gives 6-9 months, Akbar gives 1 year), after which the chest is larger. In malnourished children the crossover is delayed.
- Small head (microcephaly): small brain, craniosynostosis, congenital infection; relate it to the child's overall size.
- Large head: hydrocephalus, megalencephaly, familial.
Other measures
- Mid-upper arm circumference (MUAC): stays almost constant from 1 to 5 years, so it can be used without knowing the age (see the malnutrition chapter).
- Skinfold thickness (triceps), upper to lower segment ratio and arm span (body proportions).
- Anterior fontanelle: a large fontanelle or late closure suggests hypothyroidism, rickets or hydrocephalus, and is also seen in Down syndrome.
Teeth
- First deciduous tooth (lower central incisor) at about 6 months; all 20 milk teeth by about 2.5 years.
- Shedding starts at about 6 years and is complete by about 12 years.
- Teeth are a poor guide to growth because eruption varies widely. Delayed eruption: hypothyroidism, rickets, malnutrition.
Growth charts and percentiles
The growth chart (the "road to health" chart, first designed by David Morley) is a visual record of growth for longitudinal follow-up of one child.
Centiles and Z-scores
- A centile tells you the percentage of healthy children of the same age and sex who fall below that value. On the 25th centile, 25% of children are smaller.
- Normal range is usually taken as between the 3rd and 97th centiles (about ±2 SD). Some charts use the 0.4th and 99.6th lines.
- A Z-score (SD score) = (child's value − median) ÷ SD. Below −2 is low; below −3 is severely low.
Which chart?
- WHO Child Growth Standards (2006) for 0-5 years, built from healthy breastfed children in six countries (Multicentre Growth Reference Study). They show how children should grow in good conditions, whatever their ethnicity.
- For older children, CDC or WHO references to 19-20 years, including BMI-for-age.
- Use corrected age for preterm babies until about 2 years.
Uses of a growth chart (Park)
Growth monitoring, early detection of high-risk children (malnutrition shows on the chart before clinical signs), planning, educating the mother, deciding action, evaluating treatment, and teaching.
How often to weigh (Park)
Monthly in the first year, every 2 months in the second year, then every 3 months up to 5 years.
"Lines, not dots." One dot says nothing; the line of dots tells the story.
Indices that separate acute and chronic undernutrition
| Index | Low value is called | What it means |
|---|---|---|
| Weight for age | Underweight | Mixed acute and chronic; used for screening |
| Height for age | Stunting | Chronic or past undernutrition |
| Weight for height | Wasting | Acute undernutrition |
A child who is stunted but not wasted has had long-standing undernutrition but is not acutely starving now. Weight for height and MUAC are independent of age, so they work when the date of birth is unknown.
Factors influencing growth
| Group | Examples |
|---|---|
| Genetic | Parental height, sex, ethnicity, chromosomal disorders (Turner, Down) |
| Prenatal | Maternal nutrition, smoking, infection (rubella, syphilis), placental problems, low birth weight |
| Nutrition | The most important modifiable factor worldwide |
| Infection and parasites | Diarrhoea, measles, worms (roundworm steals nutrients) |
| Hormones | Growth hormone, thyroxine, insulin (fetal), sex steroids (puberty) |
| Chronic disease | Cyanotic heart disease, renal failure, coeliac disease, inflammatory bowel disease, poorly controlled diabetes, severe asthma |
| Socio-economic and emotional | Poverty, housing, sunlight, birth order and spacing, psychosocial deprivation |
Worldwide, malnutrition is the commonest cause of poor growth and short stature.
Red flags of abnormal growth
- Weight, height or head circumference below the 0.4th or 2nd-3rd centile, or above the 99.6th.
- Crossing (falling through) two major centile lines.
- Failure to thrive (Nelson): weight that falls or stays below the 3rd centile, falls across two major centile lines, or is below 80% of the median weight for height.
- Height velocity below about 5 cm a year after infancy.
- Height far below the mid-parental (target) range.
- Disproportion (short limbs or trunk) suggesting skeletal dysplasia.
- Head growing too fast (hydrocephalus) or too slowly (microcephaly).
- Signs of puberty too early or absent too late.
Short stature
Definition: height below the 3rd (or 5th) centile for age and sex, judged against family height. Two main groups: small but growing at a normal rate, and small and growing slowly.
| Feature | Familial short stature | Constitutional delay of growth and puberty |
|---|---|---|
| Family history | Short parent(s) | Parent with late puberty ("late bloomer") |
| Growth velocity | Normal | Normal |
| Bone age | Equal to chronological age | Delayed (equals height age) |
| Puberty | Normal timing | Late |
| Final height | Short, within family range | Normal |
| Sex | Either | Much commoner in boys |
| Treatment | Reassurance | Reassurance; short course of low-dose testosterone in some boys |
Pathological causes: undernutrition, psychosocial deprivation, chronic illness, malabsorption (coeliac, Crohn), endocrine (hypothyroidism, GH deficiency, Cushing syndrome, usually steroid-induced), syndromes (Turner, Down, Prader-Willi), skeletal dysplasias (achondroplasia), rickets, inborn errors.
- Proportionate short stature: endocrine, nutritional, chronic disease.
- Disproportionate: skeletal dysplasia.
- Hypothyroidism and GH deficiency give slow velocity with markedly delayed bone age.
- Check thyroid function in almost every short child, because it is easy to treat.
- Think of Turner syndrome in any short girl, even without typical features; do a karyotype.
First-line tests: FBC, ESR, urinalysis, urea and creatinine, thyroid function, bone age X-ray (left hand and wrist); then karyotype (girls), coeliac screen, calcium, phosphate and ALP, GH stimulation tests if velocity is low.
Mid-parental height (Nelson: the parents' average height plus 2.5 inches for a boy, minus 2.5 inches for a girl; about 6.5 cm): boys = (father + mother + 13) ÷ 2; girls = (father + mother − 13) ÷ 2, in cm.
Father 175 cm, mother 160 cm
Boy: (175 + 160 + 13) ÷ 2 = 174 cm
Girl: (175 + 160 − 13) ÷ 2 = 161 cm
GH treatment has no role in constitutional delay or familial short stature. In GH deficiency the response to replacement (velocity rising from under 5 to 7-8 cm a year) confirms the diagnosis.
Puberty and Tanner staging
Tanner (sexual maturity) staging grades breasts and pubic hair in girls and genitalia and pubic hair in boys from stage 1 (prepubertal) to stage 5 (adult).
| Stage | Girls: breasts | Boys: genitalia | Pubic hair (both) |
|---|---|---|---|
| 1 | Preadolescent; papilla elevated only | Prepubertal; testes under about 4 mL | None |
| 2 | Breast bud: breast and papilla raised as a small mound, areola widens | Testes and scrotum enlarge, scrotal skin reddens and changes texture | Sparse, long, slightly dark, downy hair at labia or base of penis |
| 3 | Further growth of breast and areola, no separation of contours | Penis grows in length; testes keep growing | Darker, coarser, curlier, spreads over pubes |
| 4 | Areola and papilla form a secondary mound above the breast | Penis grows in breadth, glans develops, scrotum darkens | Adult type but not on thighs |
| 5 | Mature; areola recedes to the breast contour, papilla projects | Adult size and shape | Adult in amount, spreads to medial thighs |
Key timings
- First sign of puberty: girls, breast budding (thelarche); boys, testicular enlargement (4 mL or more).
- Girls start earlier. The height spurt is early in girls (around breast stage 2-3) and late in boys (genital stage 4, up to about 10 cm a year).
- Menarche comes about 2 years after thelarche, usually at breast stage 4, after peak height velocity; growth then slows.
- Final height: girls by about 16, boys by about 18-19 years.
- The Prader orchidometer measures testicular volume.
Early and late puberty
| Problem | Definition | Main causes |
|---|---|---|
| Precocious puberty | Signs before 8 years in girls, 9 years in boys | Central (GnRH-dependent): mostly idiopathic in girls; CNS lesion more likely in boys (hamartoma, tumour, hydrocephalus) → MRI brain. Peripheral: CAH, adrenal or gonadal tumour, McCune-Albright, exogenous oestrogen |
| Delayed puberty | No signs by 13 years in girls (or no menarche by 16); by 14 years in boys | Constitutional delay (commonest), chronic illness, undernutrition, hypothyroidism, Turner syndrome, Klinefelter syndrome, Kallmann syndrome |
- Premature thelarche: isolated breast growth in girls under about 2 years; benign, no growth spurt.
- Premature adrenarche: pubic hair or body odour before 8 years without virilisation; benign, but later PCOS risk.
"Girls Bud, Boys Balls": the first pubertal sign is breast bud in girls and testicular enlargement in boys.
Expect: birth weight doubled at 5 months, tripled at 1 year and quadrupled at 2 years; length 50 cm at birth and 75 cm at 1 year; head circumference 34-35 cm at birth and 47 cm at 1 year; head-chest crossover; weight and height formulas; causes of a large or late-closing anterior fontanelle; length under 2 years and height after; height for chronic and weight for acute nutrition; stunting, wasting and underweight; centile limits and crossing two centile lines; familial short stature (normal bone age) versus constitutional delay (delayed bone age, late puberty, normal final height); hypothyroidism and Turner syndrome in a short child; Tanner stages; first signs of puberty; age cut-offs for precocious and delayed puberty.
Quick revision
- Weight: doubled 5 months, tripled 1 year, quadrupled 2 years; about 2 kg a year to puberty.
- Length 50 → 75 cm in year 1; 100 cm at 4 years; height = age × 6 + 77 (2-12 years).
- Head 34-35 cm → 47 cm at 1 year; equals chest by 6-12 months.
- Large or late-closing fontanelle: hypothyroidism, rickets, hydrocephalus.
- Normal range 3rd-97th centile; crossing two centile lines is a red flag.
- Stunting = chronic; wasting = acute; underweight = mixed.
- Familial short stature: normal bone age; constitutional delay: delayed bone age, late puberty, normal final height.
- Puberty starts with breast bud (girls) and testes 4 mL or more (boys); precocious before 8/9 years, delayed after 13/14 years.
Written by The House Job from standard references (Basis of Paediatrics by Pervez Akbar; Nelson Essentials of Paediatrics; Park's Preventive and Social Medicine).
FAQ
Which single measurement is best for monitoring growth?
Weight, plotted serially on a growth chart, because it is the most sensitive and changes first.
How do you tell familial short stature from constitutional delay?
Both grow at a normal rate, but bone age is normal in familial short stature and delayed in constitutional delay, where puberty is late and final height is normal.
When should a short child be investigated?
When height is below the 3rd centile and well below the family target, growth velocity is slow, the child is crossing centiles down, or there are features of disease or disproportion.
What is the first sign of puberty in each sex?
Breast budding in girls and testicular enlargement to 4 mL or more in boys.