The norm of the weight of a newborn child is one of the criteria for assessing his maturity. After the birth of the child, they are weighed, the figures obtained are checked against the norm corresponding to the gestational age. Based on the results obtained, one can judge physical development. If there are deviations in one direction or another, it is necessary to find the reason. In the article, we will talk about the calculation rules and situations when you need to take some action.

Newborn’s Birth Weight

Weight norms are average figures. Several factors affect its values. The first is gender. We present tables developed by the World Health Organization. These tables provide numerical values ​​and ratings: very low, low, below average, average, above average, high, very high.

We want below average to above average values. All except this are deviations that require an analysis of the situation together with a doctor.

Please note that the indicators are only suitable for full-term newborns. For premature babies, there is a system for assessing physical development.

Boys weight norms

Indicator scoreVery lowLowBelow the averageMiddleAbove averageTallVery tall
Body weight, kgs2.

Thus, for boys, a body weight of 2.9 to 3.9 kg is considered normal. Below 2.9 kg – – deficiency (hypotrophy), above 3.9 kg – excess, that is, paratrophy.

WHO table for boys

Weight norms in girls

Indicator scoreVery lowLowBelow the averageMiddleAbove averageTallVery tall
Body weight, kgs2.

WHO table for girls

We see that the normal weight for female newborns is 2.8 – 3.7 kg.

Weight Loss in the Early Days

On the first day in the maternity hospital, the child loses his grams. This happens for several reasons:

  1. The intestines are cleared of meconium, the original feces, within three to four days. Meconium accumulates in the intestines during pregnancy;
  2. The first days the mother produces colostrum. Its amount is small, but due to its concentrated composition, colostrum fully satisfies the nutritional needs of a newborn, but there is little water in it;
  3. Physiological loss of fluid through the skin. In the womb, the baby is surrounded by amniotic fluid and its tissues contain a lot of moisture. After birth, excess moisture is lost by the skin, pores and lungs.
  4. Swelling of tissues that occurs during childbirth go away.

A baby can lose 10% of its original body weight within 4 to 5 days. This does not mean that he is losing weight. On the contrary, everything unnecessary goes away: meconium, edema, excess fluid. Premature babies lose more weight than full-term babies: up to 15% or more. If your newborn baby loses more than this figure, the neonatologist will definitely pay attention to this and take the necessary measures to identify the cause and eliminate it.

Loss of excess moisture is not harmful to the body. On 3 – 4 days in multiparous, in primiparous a little later, milk appears. Mom’s milk contains enough liquid, so there is no need to add additional water to the baby. The main thing is to feed him on demand so that he gets enough nourishment according to his needs.

Pay attention to the color of the skin and their color, the number of urinations and their volume (how many times you change diapers). If all these parameters correspond to the norm, then there is no reason to worry.

Formula for Calculating the Weight of a Newborn

The Quetelet index can be applied to people of any age, not just newborns. But babies have their own analysis system. To calculate, we need to know the baby’s height in centimeters and his body weight in grams.

For example, the weight of a newborn is 3300 g and the height is 51 cm. 3300: 51 = 65

The Quetelet index turned out to be 65. The mean values ​​are 60 – 70. This means that our theoretical patient is all right. If the figure turns out to be above or below these limits, consult your pediatrician. Please note that the formula only applies to babies who were born on time.

Newborn Weight Norms According to WHO Standards for Boys

How Many Grams per Month Should a Child Gain

The formula takes into account the average monthly weight gain – 800 g. For an accurate calculation:

  • from 1 month to 6 months: add 800 x the number of months to the values ​​at birth. For example, a girl was born with an ideal weight of 3,200 g. By 1 month she will weigh approximately 4,000 g, and by two – 4,800 g (3,200 + 800 x 2 = 4,800);
  • from 6 months: birth weight + 800 x 6 + 400 x (number of months – 6), where we first calculate the indicators by 6 months of age, and sum it up with body weight after six months. This means that by 8 months our baby will weigh 8 800 g.

You can also use the WHO tablets for boys and girls: they have values ​​from birth to 13 weeks.

What Affects Body Weight

Mass depends on many factors. Some of them contribute to overweight, and some on the contrary – to deficiency. Let’s list them:

  1. Gestational age, or gestational age. If the baby was born earlier or later than the term, it is obvious that his performance will differ from the accepted standards;
  2. The state of health of the mother, the presence or absence of diseases;
  3. The nature of food and lifestyle;
  4. Taking medications;
  5. Constitution of both parents;
  6. The condition of the child himself, both during pregnancy (intrauterine problems), and during childbirth and immediately after them;
  7. Baby’s gender.

Check Weighing

Control weighing is done when you need to know if your baby has enough breast milk. In the case of artificial feeding, there are no problems with controlling the amount of food taken.

The weighing rules are as follows:

  • we take measurements before and after one feeding;
  • we try to use the same scales;
  • we make sure that the baby is in the same clothes;
  • if during feeding the baby gets dirty in the diaper, you do not need to change or remove it;
  • we take measurements several times in a row during the day or on different days to get a reliable result.

If the results show that there is not enough milk, then the mother needs to think about increasing lactation. Ask the pediatrician who looks after your newborn for a medication.

Up to 10 days, the calculation is carried out according to the formula: milk volume = 2% of body weight multiplied by the number of days of life. For example, our fictional baby weighing 3,200 on the fifth day of life should eat 320 ml of milk per day. We divide this figure by the number of feedings.

For older children, a different method is used. From 2 to 4 weeks, the required volume of milk is 1/5 of the body weight per day, from 6 weeks to 4 months – 1/6.

Is it Worth Worrying About a Deviation From the Norm

Anthropometric data provide some information about the development of the baby. You compare your numbers with the average of a healthy baby: it is desirable that they be included in the normal values. But there may be deviations: excess or deficit. Fortunately, not in all cases they speak of pathology.


Chubby cheeks and an abundance of folds have long been considered a sign of good health. But medicine says the opposite: you should be wary if the bodyweight of your little one exceeds average values. The reasons may be as follows:

  • the expectant mother eats for two, while this is not the most healthy food;
  • postmaturity;
  • hereditary factor;
  • diabetes mellitus in a pregnant woman;
  • swelling in the baby.

The pregnant woman is monitored by an obstetrician-gynecologist for the entire period and undergoes examinations and tests. After childbirth, neonatologists and pediatricians take the baton: they diagnose the newborn, monitor its development.

If you follow all the doctor’s prescriptions, there are no illnesses, no abnormalities were found in the baby either, but the values ​​are higher than normal, then there is no reason for worry. Lead an active lifestyle, accustom your child to such a regime. Over time, his body weight should return to normal – keep track of this with your doctor. After all, overweight and obesity are not so rare among children. In addition, a large mass is a load on the child’s joints, then it will be difficult for him to sit down, crawl, and then walk.


The disadvantage can be caused by:

  • nutritional deficiency during gestation;
  • chronic diseases in mom;
  • bad habits of mom;
  • taking drugs, such as antimetabolites;
  • placental abnormalities;
  • illness of the child.

In these cases, they talk about intrauterine growth retardation: the fetus does not receive enough nutrients, therefore dystrophic changes develop. Depending on the cause, the doctor selects the treatment.

Newborn Weight and Parental Physique

Constitutional characteristics are inherited, as are hair color, eye colour, or personality. But this does not mean that the baby will be a copy of mom or dad: perhaps he will inherit the features of a distant relative.

Of course, calculating the norm for the weight of a newborn baby is important. It further affects his health, especially if the cause of the deviations is any serious illness. But if these are just features of the constitution, the baby will quickly gain weight in the future or normalise it if there was paratrophy. The main thing for him now is the care and care of mom and dad, adherence to the daily regimen, sufficient food and walks.

About Author

Tori Pearl

A recent mom, Tori kind of took rebirth after she became pregnant with her first child. Since then, she has been researching quite a lot and is trying to become a 'Perfect' mom to Danny.

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