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Baby's weight by month
Last reviewed: 04.07.2025

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The baby's weight by month is of interest to any attentive and caring mother. The indicator of the dynamics of weight gain, as well as height, are important parameters indicating the normal development of the baby.
First of all, parents need to remember the basics of mathematics in order to periodically calculate the optimal weight of their child.
Formula No. 1, which is designed to calculate the weight of a baby aged from 1 month to six months: 800 grams is multiplied by the age expressed in months, then the weight indicator that was recorded at the time of birth is added to the product. For example, weight = 800 x 3 (three months) + 3500 (the child's weight at birth). It turns out that a three-month-old child should weigh about 5900 grams. Of course, you should not panic if at this age the baby has not gained the required weight and weighs only 5500 grams, perhaps he is simply growing more intensively during this period.
Formula No. 2, which is designed to calculate the body weight of a child aged from 7 months to one year:
800 grams is multiplied by 6, then 400 grams is multiplied by the age (number of months). These two products are added together and the child's birth weight is added to them. For example, weight = 800x6 + 400x7 + 3400. It turns out that a seven-month-old child should be within 10-11 kilograms.
These formulas are indicative, more guiding than definitive as indicators of the baby’s normal development.
The weight of a child by month depends not only on the diet and feeding regimen, the dynamics of weight gain are influenced by many factors - the general condition of the body, possible diseases, digestive disorders, individual characteristics associated with the hereditary factor. If the child's parents are not distinguished by a heroic build and weigh very little, most likely, such a child will never "catch up" with standard indicators. Despite the individual weight gain schedule, each child should normally develop quite dynamically. Therefore, slow weight gain should alert attentive parents.
The main general parameters that can be used to calculate such an indicator as a child’s weight by month, and to analyze standard indicators and real figures of monthly weighing:
- By the age of five months, the baby's weight should double. For example, a baby was born weighing 3600, therefore, by five months he should weigh about 7200. It should be noted that children born with small weight indicators gain weight more dynamically. And large babies, on the contrary, gain weight a little slower. A child born with a body weight of 4100 grams, at the age of five months is not obliged to weigh 8200 grams at all, for him, a weight of 7500 or 8000 grams may be more comfortable.
- During the first three months, the baby gains about 15-200 grams per week, from 800 to 900 grams per month.
- From three months to six months, weight increases by 100-110-120 grams per week, and weight gain decreases by an average of 500 grams, that is, not 900, but 850, then 800, and so on.
- Then the weight gain becomes even smaller; from nine to twelve months of age, weight increases by 50-80 grams per week or 250-300 grams per month.
The baby's weight by month is subject to one simple rule: the older the baby becomes, the less weight he gains. Considering the typical problems for babies - digestive problems, teething and poor appetite during this period, it can be predicted that during these weeks the baby may not gain weight at all. The main indicator is a calm baby who cries only when he is hungry or unhappy with an overflowing diaper.