A number of factors influence the physical development:
1. Health.
2. The external environment.
3. Physical education.
4. Compliance with the regime of the day.
5. Nutrition.
6. Hardening.
7. Hereditary predisposition.
The weight of a full-term newborn baby is 2500-3500 gm. Within 1 year of life, the child's body weight rapidly increases. By the year it should triple.
The average values of weight gain for each month of the first half of the year are, hm:
1st month - 500-600
2nd month - 800-900
3rd month - 800
4th month - 750
5th month - 700
6th month - 650
7th month - 600
8th month - 550
9th month - 500
10th month - 450
11th month - 400
The 12th month is 350.
Approximately monthly weight gain during the first year of life can be determined by the formula:
800 g - (50 x n),
The body weight in the first year of life can be determined by the formula;
For the first six months of this formula, the body weight is:
mass at birth + (800 x n),
where n is the number of months, 800 is the average monthly weight gain during the first half of the year.
For the second half of the year the body weight is:
mass at birth + (800 x 6) (weight gain for the first half of the year) -
400 g x (n-6)
where 800 g = 6 - weight increase for the first half of the year;
n is the age in months;
400 g - the average monthly weight gain for the second half of the year.
A one-year-old child weighs 10 kg on average.
After the first year of life, the growth rate of body weight gradually decreases, increase only during puberty.
The body weight of a child aged 2-11 years can be determined by the formula:
10 kg + (2 x n),
where n is the number of years.
So, a child in 10 years must weigh:
10 kg + (2 x 10) = 30 kg.
Height (body length).
At 3 months, the average height is 60 cm. In 9 months, 70 cm, a year - 75 cm for boys and 1-2 cm less for girls.
1, 2, 3 - every month for 3 cm = 9 cm.
4, 5, 6 - every month for 2.5 cm = 7.5 cm.
7, 8, 9 - every month for 1.5 cm = 4.5 cm.
10, 11, 12 - every month for 1 cm = 3 cm.
Consequently, on average the child grows by 24-25 cm (74-77 cm).
Different parts of the child's body grow unequally, the most intense are the lower limbs, their length increases fivefold during the entire period of growth, the length of the upper limbs 4 times, the trunk 3 times, and head height 2 times.
The first period of intensive growth occurs in 5-6 years.
The second extension is 12-16 years.
The average height of a child under 4 years is determined by the formula :
100 cm-8 (4-n),
where n is the number of years, 100 cm is the growth of the child in 4 years.
If the child is more than 4 years old , then its growth is equal to:
100 cm + 6 (4 - n),
where n is the number of years.
Circumference of head and thorax
The circumference of the newborn's head is 32-34 cm. The head circumference increases especially rapidly in the first months of life:
in the first trimester - 2 cm per month;
in the second trimester - 1 cm per month;
in the third half of the year - 0.5 cm per month.
Mean head circumference in children of different ages
Age - Head circumference, cm
Newborn 34-35
3 months - 40
6 months - 43
12 months - 46
2 years - 48
4 years - 50
12 years old - 52
The circumference of the chest in a newborn baby is 1-2 cm less than the circumference of the head. Up to 4 months there is an equalization of the thorax with the head, later the circumference of the thorax increases faster than the circumference of the head.
The circumference of the abdomen should be slightly smaller (by 1 cm) in the circumference of the chest. This indicator is informative up to 3 years.