Physical growth of infants and children

Physical growth includes reaching full height and corresponding body weight, as well as increasing the size of all body organs (except lymphoid tissue, which decreases in size). Growth shows two defined growth phases from birth to adolescence:

Phase 1 (from birth to 1-2 years of age): this phase is characterized by a high but decreasing growth rate over time.

Phase 2 (from the second year of life to puberty): In this phase, there is a constant annual growth in size.


1. Grummer-Strawn LM, Reinold C, Krebs NF, Centers for Disease Control and Prevention (CDC): Use of World Health Organization and CDC growth charts for children aged 0-59 months in the United States. MMWR Recomm Rep 10(RR-9):1-15, 2010. Clarification and additional information. MMWR Recomm Rep 59(36): 1184, 2010.

Body length

Body length is measured for children who cannot yet stand, body height is measured once the child can stand. Normally, the length of a mature infant increases until the 5. Month of life by about 30% and> 50% by 12. month of life; infants grow 25 cm in the first year; doubling of birth length occurs at 5 years. Most boys reach half adult height by two years of age, most girls by 19 months of age.

To assess growth, the growth rate is the more sensitive parameter compared to the size measurement at different time points. Normally, healthy mature infants and children grow between birth and the 6. Approximately 2.5 cm per month between 7 months of age, 1.3 cm per month between 7 months of age. and 12. month and ca. 7.6 cm a year between the 12. month and the 10. Year of life.

Before the age of 12. After the first month of life, the growth rate varies and is also partly dependent on perinatal factors (z. B. Prematurity Premature infant An infant who is born before 37. week of gestation is considered a premature infant. Preterm birth is defined by the gestational ages at which infants are born. Formerly. Learn More ). From the age of 12. From the first month of life, size is predominantly determined only genetically; the growth rate remains constant until puberty. The size of a child in relation to its peers usually remains the same.

Some SGA infants SGA infants whose weight in relation to the gestational age of the 10. The percentiles below the preterm birth age are classified as small for gestational age. Complications include perinatal asphyxia, meconium aspiration. Learn more tend to remain smaller throughout their lives than children of the same gestational age whose weight at birth was normal. The difference in growth rate is small in boys and girls during infancy and childhood.

Extremities grow faster than the trunk of the body, resulting in a gradual change in proportions. The ratio of apex pubis to pubic heel is 1.7 at birth and then decreases to 1.5 at 12 months, to 1.2 at 5 years, and 1.0 at 7 years of age.


Body weight follows a similar pattern. Normal and term newborns lose 5-8% of their birth weight in the days after birth, which is regained within about 2 weeks. Thereafter, they increase in weight until 3. month of life approx. 14-28 g a day, then between the 3. and 12. The total weight of the child is 4000 g from the 7th month of life, which leads to a doubling of the birth weight at 5 months, a tripling at 12 months and almost a quadrupling at 2 years of age. Between the 2. Between the age of 2 and puberty, the increase is 2 kg per year. In the context of the recent epidemic increase in childhood obesity, obesity refers to overweight with a body mass index (BMI) ≥ 30 kg/m2 or greater. Associated complications include cardiovascular disease (especially in those with excess abdominal fat). Learn more (see table Changes in prevelance vpn obesity according to NHANES Changes in prevalence of obesity according to NHANES Physical growth includes attaining full body height and corresponding body weight, as well as increasing the size of all body organs (except for lymphoid tissue. Learn more ) resulted in much larger weight gains, even in very young children. Typically, boys are taller and heavier than girls after growth is complete because they have a longer prepubertal growth period, a faster maximum growth rate during the pubertal growth spurt, and longer-lasting growth during adolescence.

Head circumference

Head circumference reflects brain size and is routinely measured up to 36 months of age. At birth, the brain is about 25% of adult size, with a head circumference of 35 cm. In the first year, the head circumference increases on average by 1 cm per month, with the fastest growth in the first 8 months of life. At 12 months, the brain has reached half of its postnatal growth and 75% of adult size. Over the next two years, head circumference increases by 3.5 cm. At 2 years of age, the brain is 80% of adult size and at 7 years of age it is 90% of adult size.

Composition of the body

Body composition (the ratio of body fat to body water) changes and affects the distribution of drug volume Drug distribution in the body Pharmacokinetics includes drug absorption, distribution, metabolism, and excretion. There are important age-related differences in pharmacokinetics. The resorption. Learn more . The percentage of body fat increases rapidly from 13% at birth to 20-25% at 12 months of age, leading to the rounded appearance at this age. As a result, the body fat percentage slowly decreases again, dropping to 13% in preadolescence. Until the onset of puberty, there is again a slow increase, before the proportion then drops again, especially in boys. After puberty, body fat percentage remains the same in girls, while it decreases slightly in boys.

The proportion of body water in relation to body weight at birth is 70%, then drops to 12. The proportion of permanent teeth decreases to 61% by the first month of life (similar to the proportion in adults). This change is based entirely on the decrease in extracellular fluid (ECF) from 45 to 28% of body weight. Intracellular fluid remains relatively constant. After 12 months of age, there is a slow and variable decrease in extracellular fluid to adult levels of about 20% and an increase in intracellular fluid to adult levels of about 40%. The relatively greater proportion of body water, the higher turnover rate, and the comparatively greater perspiratio insensibilis (because of the relatively greater body surface area) mean that infants are more susceptible to fluid deficiency than older children and adults.

Tooth eruption

The timing of tooth eruption is variable (see table: Times of tooth eruption Times of tooth eruption Physical growth includes attainment of full body height and corresponding body weight, as well as increases in the size of all body organs (except lymphoid tissue. Learn more ), primarily due to genetic factors. In general, normal infants should have 6 teeth at 12 months of age, 12 teeth at 18 months, 16 teeth at 2 years of age, and all 20 teeth at 2½ years of age. Permanent teeth replace deciduous teeth between 5. and the 13. Year of life. The eruption of deciduous teeth is the same in boys and girls; in contrast, permanent teeth usually come in earlier in girls. Tooth eruption may be due to family history or rickets Hypophosphatemic rickets is a hereditary disorder characterized by hypophosphatemia, impaired intestinal calcium adsorption, and rickets or osteomalacia. Learn more , Hypopituitarism Growth hormone deficiency in children Growth hormone deficiency is the most common pituitary hormone deficiency in children and can be isolated or occur along with deficiency of other pituitary hormones. Growth hormone deficiency leads. Learn more , Hypothyroidism Hypothyroidism in infants and children Hypothyroidism is a deficiency of thyroid hormones. Symptoms in infants include poor eating habits and stunted growth. The symptoms in children and young people are. Learn more or Down syndrome Down syndrome (trisomy 21) Down syndrome is an abnormality of chromosome 21 that can cause mental retardation, microcephaly, short stature and characteristic appearance. The diagnosis is made on the basis of clinical. Learn more be delayed. Supernumerary and missing teeth are probably norm variants.

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