Glossary

Child development glossary

Plain-language, evidence-based explanations of the terms you meet across growth, maturation, height prediction, sport, nutrition and digital health. Tap a term to read the full article.

Growth & Height

12 terms

Core growth concepts: percentile, growth curve, growth velocity and short stature.

Percentile

A percentile shows where your child’s height or weight stands among peers of the same age and sex. The trend over time matters more than a single measurement.

Growth Chart (Percentile Graph)

A growth chart plots a child’s height, weight and head circumference over time on percentile bands. It is the most fundamental tool for tracking healthy growth.

Growth Velocity

Growth velocity shows how many centimetres a child grows per year. As much as height itself — sometimes more — the speed of growth carries diagnostic value.

Short Stature

Short stature is height markedly below same-age peers. It is most often familial or constitutional; a minority is due to causes that should be evaluated.

Z-score (Standard Deviation Score, SDS)

A z-score shows how many standard deviations a measurement is from the mean. It is the more precise, statistical sibling of the percentile, preferred at the extremes.

Catch-up Growth

Catch-up growth is when, after an obstacle is removed, a child grows faster than expected and returns to their own genetic channel.

Head circumference is an indirect indicator of brain growth, especially in the early years. Like height and weight, it is assessed by whether the child follows their own channel on the percentile curve.

Growth Hormone

Growth hormone plays a central role in a child’s height growth. Its deficiency is a rare cause of short stature and requires careful clinical evaluation.

Tall Stature

Tall stature is height markedly above same-age peers. It is most often familial or due to early maturation; rarely there are causes that should be evaluated.

Coeliac Disease and Growth

Coeliac disease impairs absorption in the gut through an immune reaction to gluten. In children it is one of the causes of growth faltering and short stature that should be recognised.

Thyroid and Growth

Thyroid hormones are essential for a child’s height growth and development. An underactive thyroid (hypothyroidism) can slow growth; it is one of the correctable causes of short stature.

Prematurity and Birth Weight (SGA/LGA)

Preterm birth and birth weight shape a child’s early growth. Corrected age and catch-up growth are the keys to interpreting these babies’ growth correctly.

Maturation & Puberty

10 terms

Biological maturation, peak height velocity (PHV), Tanner stages, bone age and pubertal timing.

Maturation (Biological Maturity)

Maturation is a child’s level of biological maturity. Two children of the same age can differ by 2–4 years in maturity; it is more decisive than calendar age in sport and height prediction.

PHV — Growth Spurt (Peak Height Velocity)

PHV is the period of adolescence when height grows fastest. It occurs on average around age ~12 in girls and ~14 in boys; injury risk rises in this window and training load should be adjusted.

Tanner Stage

The Tanner stage is a clinical scale that classifies pubertal development into 5 stages (Stage I: pre-pubertal → Stage V: adult maturity). It is usually assessed by a doctor.

Bone Age (Skeletal Age)

Bone age is the level of skeletal maturation determined by a hand-wrist X-ray. It can be ahead of or behind calendar age and shows the remaining growth potential.

Precocious Puberty (Early Puberty)

Precocious puberty is the onset of pubertal signs before age 8 in girls and 9 in boys. It is a situation that should be evaluated; not every early development is the same thing.

Delayed Puberty

Delayed puberty is the absence of pubertal signs by age 13 in girls and 14 in boys. Its most common cause is benign constitutional delay; even so, it should be evaluated.

Menarche (First Period)

Menarche is a girl’s first menstrual period. It is a relatively late milestone in the journey of puberty and usually comes after the peak of the growth spurt has passed.

Testicular Volume and the Orchidometer

An increase in testicular volume is the first objective sign of puberty in boys. The orchidometer measures this volume and helps determine that puberty has begun and which stage it is at.

Adrenarche

Adrenarche is the rise of weak male hormones as the adrenal glands mature. It can cause mild underarm/groin hair and body odour; it is different from true puberty.

Gynaecomastia in Adolescents (Breast Tissue)

Temporary breast-tissue development (gynaecomastia) is common in pubertal boys and mostly benign. It usually regresses on its own as the hormones settle.

Height Prediction Methods

9 terms

Mid-parental, Khamis-Roche, Bayley-Pinneau, Greulich-Pyle and the Neyzi reference.

Mid-Parental Height (Target Height)

Mid-parental height is the genetic height expectation calculated from the mother’s and father’s heights. On its own it is not a precise prediction; it gives a familial band of roughly ±8.5 cm.

The Khamis-Roche Method

Khamis-Roche is a scientific method that predicts adult height from age, height, weight and parental heights without needing an X-ray (ages 4–17.5). It is one of the most accurate X-ray-free methods.

The Bayley-Pinneau Method

Bayley-Pinneau is the classic method that predicts adult height using bone age (a hand-wrist X-ray). It directly takes the remaining growth potential into account.

The Greulich-Pyle Atlas

Greulich-Pyle is the classic method that determines bone age by comparing a hand-wrist X-ray with standard atlas images. It is one of the fundamental references for bone-age assessment.

The Neyzi 2008 Growth Reference

Neyzi 2008 is the national growth reference for Turkish children. It uses Turkey-specific values for percentile and z-score calculations; it is the fundamental source for local assessment.

PAH / %PAH — Projected Adult Height

PAH (Projected Adult Height) is the estimated adult height. %PAH is a maturation indicator showing what percentage of this projected adult height the child’s current height has reached.

Maturity Offset (The Mirwald Method)

Maturity offset is an X-ray-free method that estimates, in years, how close a child is to their growth spurt (PHV). It predicts maturation from anthropometric measurements.

The Tanner-Whitehouse (TW) Method

Tanner-Whitehouse is an analytical method that determines bone age by giving each bone in the hand-wrist X-ray an individual maturity score. It is an alternative standard to Greulich-Pyle.

Combined (Ensemble) Height Prediction

Combined prediction brings different height-prediction methods together to produce a single result and a confidence interval. When the methods agree, confidence rises; when they diverge, it signals uncertainty.

Sport & Training

12 terms

LTAD, bio-banding, sport readiness, early specialisation and training-load concepts.

LTAD — Long-Term Athletic Development

LTAD (Long-Term Athletic Development) is a developmental model that defines training stages suited to a child’s age and maturity. It prioritises long-term, safe development over early results.

Bio-banding (Grouping by Maturity)

Bio-banding is grouping children by biological maturity rather than calendar age. It lets early and late developers compete more fairly and safely.

Sport Readiness

Sport readiness is the assessment of how physically and developmentally ready a child is for a particular sport and load level. It considers growth, maturation and nutrition together.

Early Specialisation

Early specialisation is when a child concentrates on a single sport year-round at a young age. It raises the risk of overuse injuries, burnout and dropping out early.

Relative Age Effect

The relative age effect is when children born in the earlier months of the year — being more mature — enjoy a selection advantage within the same age group. It can hide true talent.

Deload (Load-Reduction Week)

A deload is a period in the training programme where the load is deliberately reduced. It supports recovery and prevents injury and overload.

Strength Training in Children

With proper supervision and technique, strength training is safe and beneficial for children. The aim is not to lift heavy but to develop movement quality, coordination and injury prevention.

Neuromuscular Warm-up (Injury Prevention)

A neuromuscular warm-up is a structured programme that replaces a general run. With running, balance, strength and jump-landing elements, it markedly reduces injuries.

Plyometric Training (Jump Work)

Plyometric training develops power and landing control through jumps and rapid muscle contractions. In children, applied with quality and low volume, it is safe and beneficial.

Agility, Balance and Coordination (ABC)

Agility, balance and coordination are the shared fundamental skills of all sports. This “movement literacy”, gained through play in early childhood, forms the ground for later development.

Flexibility and Mobility

Flexibility and joint mobility matter for healthy movement and injury prevention. In children, a dynamic warm-up and controlled stretching are preferred over excessive static stretching.

Overtraining and Burnout

Overtraining is a prolonged disruption of the balance between load and recovery. In children it can lead to a drop in performance, constant fatigue, injury and dropping out of sport.

Nutrition

10 terms

Childhood BMI percentile, the Mediterranean diet, KIDMED and young-athlete nutrition.

BMI in Children (BMI Percentile)

In children, BMI (body mass index) is not read on its own but as a percentile for age and sex. It reflects the weight-for-height balance; it is the trend, not a single measurement, that matters.

KIDMED Index

KIDMED is a 16-item index that measures adherence to the Mediterranean diet in children and adolescents. A higher score indicates a healthier eating pattern.

The Mediterranean Diet (in Children)

The Mediterranean diet is an eating pattern centred on vegetables, fruit, whole grains, pulses, fish and olive oil. It is regarded as a strong model for healthy growth and development in children.

Young Athlete Nutrition

Nutrition for young athletes is built on adequate energy, balanced macronutrients and good hydration. The aim is healthy growth and energy balance more than performance.

Bone Health: Calcium and Vitamin D

Childhood and adolescence are the period in which most of the bone mass that lasts a lifetime is gained. Calcium, vitamin D and weight-bearing movement are the foundation of this process.

Iron Deficiency in Children

Iron deficiency is one of the most common nutritional deficiencies in children. It can affect fatigue, attention and development; it improves with nutrition and, where needed, treatment.

RED-S (Relative Energy Deficiency)

RED-S is when the energy taken in is not enough to meet both training and growth. In young athletes it can adversely affect growth, bone health, menstrual regularity and performance.

The Importance of Breakfast in Children

Breakfast supports a child to start the day with energy, and aids attention and learning. A regular, balanced breakfast is one of the cornerstones of a healthy eating pattern.

Sugary Drinks and Child Health

Sugary drinks are one of the biggest sources of added sugar in children’s diets. They provide high calories without filling them up; replacing them with water is one of the most effective healthy steps.

Childhood Obesity

Childhood obesity is excess body fat to a degree that can affect health. Screening is done with BMI percentile and the waist-to-height ratio; the approach is not blaming but focused on health and habits.

Digital Health & Lifestyle

7 terms

Lifestyle determinants such as screen time, sleep and physical activity.