Infant weight chart by week
Average baby weight: Chart and development
Weight is one indicator of good nutrition and physical development. It can therefore be helpful to know about babies’ average weight month by month.
First, it is worth noting that average weight is not “normal” weight. Just like adults, babies come in all shapes and sizes. If a baby’s weight is in a lower percentile, this does not necessarily signal a problem with their growth or physical development. With this in mind, using a weight chart can help a person generally track their baby’s growth.
The Centers for Disease Control and Prevention (CDC) recommend using the World Health Organization (WHO) weight chart for babies up to 2 years of age.
This article describes the average weight of a baby month by month from birth. It also explores what can affect a baby’s weight.
According to the WHO, the average birth weight of a full-term male baby is 7 pounds (lb) 6 ounces (oz), or 3.3 kilograms (kg). The average birth weight of a full-term female is 7 lb 2 oz, or 3. 2 kg.
The average weight of a baby born at 37–40 weeks ranges from 5 lb 8 oz to 8 lb 13 oz. This is 2.5 to 4 kg.
At delivery, experts consider a low birth weight to be less than 5 lb 8 oz, or 2.5 kg.
It is common for babies to lose around 10% of their weight shortly after birth. This decrease is mostly due to fluid loss and usually nothing to worry about. Most babies gain back this weight within 1 week.
Weight charts can help a person tell what percentile their baby’s weight falls into. For example, if their weight is in the 60th percentile, it means that 40% of babies of the same age and sex weigh more, and 60% of these babies weigh less.
This does not necessarily mean that any baby weighs too much or too little. It can simply indicate where a baby’s weight falls on a spectrum.
The chart below shows baby weights in the 50th percentile. This is the average weight. Male babies tend to weigh a little more than female babies, so the chart is divided by sex.
| Baby age | Female 50th percentile weight | Male 50th percentile weight |
| Birth | 7 lb 2 oz (3.2 kg) | 7 lb 6 oz (3.3 kg) |
| 1 month | 9 lb 4 oz (4.2 kg) | 9 lb 14 oz (4.5 kg) |
| 2 months | 11 lb 5 oz (5.1 kg) | 12 lb 4 oz (5.6 kg) |
| 3 months | 12 lb 14 oz (5.8 kg) | 14 lb 1 oz (6.4 kg) |
| 4 months | 14 lb 3 oz (6.4 kg) | 15 lb 7 oz (7.0 kg) |
| 5 months | 15 lb 3 oz (6.9 kg) | 16 lb 9 oz (7.5 kg) |
| 6 months | 16 lb 1 oz (7.3 kg) | 17 lb 8 oz (7.9 kg) |
| 7 months | 16 lb 14 oz (7.6 kg) | 18 lb 5 oz (8.3 kg) |
| 8 months | 17 lb 8 oz (7.9 kg) | 18 lb 15 oz (8.6 kg) |
| 9 months | 18 lb 2 oz (8.2 kg) | 19 lb 10 oz (8.9 kg) |
| 10 months | 18 lb 11 oz (8.5 kg) | 20 lb 3 oz (9. 2 kg) |
| 11 months | 19 lb 4 oz (8.7 kg) | 20 lb 12 oz (9.4 kg) |
| 12 months | 19 lb 12 oz (8.9 kg) | 21 lb 4 oz (9.6 kg) |
Babies grow and gain weight the fastest within the first 6 months of life. Although this can vary, babies tend to gain around 4–7 oz, or 113–200 grams (g), per week in the first 4–6 months.
Weight gain then slows slightly, with an average gain of around 3–5 oz (about 85–140 g) per week when the baby is 6–18 months. On average, babies triple their birth weight by their first birthday.
Growth patterns do not follow a clear schedule, however.
Some babies gain weight steadily and stay in the same percentile, or close to it, for several months. Others gain weight rapidly, signalling a growth spurt, which can happen at any time. This may move a baby into a new weight percentile.
It is important not to focus on weight as the only indicator of physical development. Other measurements of this development include the baby’s length and head circumference.
Considering all three measurements gives doctors an idea about how the baby is growing, compared with other babies of the same age and sex.
Meanwhile, it is also important to keep other developmental milestones in mind. Various checklists of milestones by age are available, including one from Pathways.org, which is endorsed by organizations such as the American Academy of Pediatrics and the National Association of Pediatric Nurse Practitioners.
For anyone looking for more information about what influences the weight of a baby, several factors can be involved, including:
Sex
Male newborns tend to be bigger than female newborns, and they typically gain weight a little faster during infancy.
Nutrition
Weight gain and growth rates can also depend on whether the baby consumes breast milk or formula.
The American Academy of Pediatrics notes that breastfed babies gain weight and grow faster than formula-fed babies during the first 6 months.
However, that rate can shift during the next 6 months.
Breastfed babies may gain weight and grow more slowly than formula-fed babies when they are aged 6 months to 1 year.
Medical conditions
Underlying health issues can cause a baby to gain weight more slowly. For example, babies with congenital heart irregularities may gain weight at a slower rate than babies without this condition.
Health issues that affect nutrient absorption or digestion, such as celiac disease, may also lead to slow weight gain.
Prematurity
Babies born prematurely may grow and gain weight more slowly during their first year than babies born at full term.
However, many babies born prematurely gain weight rapidly and “catch up” by about their first birthday.
The average birth weight for full-term male babies is 7 lb 6 oz, or 3.3 kg. For female babies born full-term, the average birth weight is 7 lb 2 oz, or 3.2 kg.
Baby weight charts can help a healthcare team track a baby’s physical development by comparing the baby’s weight with the weights of others of the same age and sex.
Still, a doctor usually looks for steady growth, rather than a target percentile, when assessing a baby’s physical development. And even if a baby’s weight is in a lower percentile, they will not necessarily be a small adult — just as longer babies do not necessarily become tall adults.
Knowing about average weights by month can help people gauge their babies’ physical development, but doctors also look for other important indicators, such as length and head circumference.
Healthcare professionals also take into account whether a baby is generally hitting other milestones on time. And by taking a detailed medical history, they can rule out any medical conditions or nutritional considerations that may be preventing a baby from gaining weight appropriately.
Average baby weight: Chart and development
Weight is one indicator of good nutrition and physical development. It can therefore be helpful to know about babies’ average weight month by month.
First, it is worth noting that average weight is not “normal” weight.
Just like adults, babies come in all shapes and sizes. If a baby’s weight is in a lower percentile, this does not necessarily signal a problem with their growth or physical development. With this in mind, using a weight chart can help a person generally track their baby’s growth.
The Centers for Disease Control and Prevention (CDC) recommend using the World Health Organization (WHO) weight chart for babies up to 2 years of age.
This article describes the average weight of a baby month by month from birth. It also explores what can affect a baby’s weight.
According to the WHO, the average birth weight of a full-term male baby is 7 pounds (lb) 6 ounces (oz), or 3.3 kilograms (kg). The average birth weight of a full-term female is 7 lb 2 oz, or 3.2 kg.
The average weight of a baby born at 37–40 weeks ranges from 5 lb 8 oz to 8 lb 13 oz. This is 2.5 to 4 kg.
At delivery, experts consider a low birth weight to be less than 5 lb 8 oz, or 2.5 kg.
It is common for babies to lose around 10% of their weight shortly after birth.
This decrease is mostly due to fluid loss and usually nothing to worry about. Most babies gain back this weight within 1 week.
Weight charts can help a person tell what percentile their baby’s weight falls into. For example, if their weight is in the 60th percentile, it means that 40% of babies of the same age and sex weigh more, and 60% of these babies weigh less.
This does not necessarily mean that any baby weighs too much or too little. It can simply indicate where a baby’s weight falls on a spectrum.
The chart below shows baby weights in the 50th percentile. This is the average weight. Male babies tend to weigh a little more than female babies, so the chart is divided by sex.
| Baby age | Female 50th percentile weight | Male 50th percentile weight |
| Birth | 7 lb 2 oz (3.2 kg) | 7 lb 6 oz (3.3 kg) |
| 1 month | 9 lb 4 oz (4.2 kg) | 9 lb 14 oz (4.5 kg) |
| 2 months | 11 lb 5 oz (5. 1 kg) | 12 lb 4 oz (5.6 kg) |
| 3 months | 12 lb 14 oz (5.8 kg) | 14 lb 1 oz (6.4 kg) |
| 4 months | 14 lb 3 oz (6.4 kg) | 15 lb 7 oz (7.0 kg) |
| 5 months | 15 lb 3 oz (6.9 kg) | 16 lb 9 oz (7.5 kg) |
| 6 months | 16 lb 1 oz (7.3 kg) | 17 lb 8 oz (7.9 kg) |
| 7 months | 16 lb 14 oz (7.6 kg) | 18 lb 5 oz (8.3 kg) |
| 8 months | 17 lb 8 oz (7.9 kg) | 18 lb 15 oz (8.6 kg) |
| 9 months | 18 lb 2 oz (8.2 kg) | 19 lb 10 oz (8.9 kg) |
| 10 months | 18 lb 11 oz (8.5 kg) | 20 lb 3 oz (9.2 kg) |
| 11 months | 19 lb 4 oz (8.7 kg) | 20 lb 12 oz (9.4 kg) |
| 12 months | 19 lb 12 oz (8.9 kg) | 21 lb 4 oz (9.6 kg) |
Babies grow and gain weight the fastest within the first 6 months of life. Although this can vary, babies tend to gain around 4–7 oz, or 113–200 grams (g), per week in the first 4–6 months.
Weight gain then slows slightly, with an average gain of around 3–5 oz (about 85–140 g) per week when the baby is 6–18 months. On average, babies triple their birth weight by their first birthday.
Growth patterns do not follow a clear schedule, however.
Some babies gain weight steadily and stay in the same percentile, or close to it, for several months. Others gain weight rapidly, signalling a growth spurt, which can happen at any time. This may move a baby into a new weight percentile.
It is important not to focus on weight as the only indicator of physical development. Other measurements of this development include the baby’s length and head circumference.
Considering all three measurements gives doctors an idea about how the baby is growing, compared with other babies of the same age and sex.
Meanwhile, it is also important to keep other developmental milestones in mind. Various checklists of milestones by age are available, including one from Pathways.
org, which is endorsed by organizations such as the American Academy of Pediatrics and the National Association of Pediatric Nurse Practitioners.
For anyone looking for more information about what influences the weight of a baby, several factors can be involved, including:
Sex
Male newborns tend to be bigger than female newborns, and they typically gain weight a little faster during infancy.
Nutrition
Weight gain and growth rates can also depend on whether the baby consumes breast milk or formula.
The American Academy of Pediatrics notes that breastfed babies gain weight and grow faster than formula-fed babies during the first 6 months.
However, that rate can shift during the next 6 months. Breastfed babies may gain weight and grow more slowly than formula-fed babies when they are aged 6 months to 1 year.
Medical conditions
Underlying health issues can cause a baby to gain weight more slowly. For example, babies with congenital heart irregularities may gain weight at a slower rate than babies without this condition.
Health issues that affect nutrient absorption or digestion, such as celiac disease, may also lead to slow weight gain.
Prematurity
Babies born prematurely may grow and gain weight more slowly during their first year than babies born at full term.
However, many babies born prematurely gain weight rapidly and “catch up” by about their first birthday.
The average birth weight for full-term male babies is 7 lb 6 oz, or 3.3 kg. For female babies born full-term, the average birth weight is 7 lb 2 oz, or 3.2 kg.
Baby weight charts can help a healthcare team track a baby’s physical development by comparing the baby’s weight with the weights of others of the same age and sex.
Still, a doctor usually looks for steady growth, rather than a target percentile, when assessing a baby’s physical development. And even if a baby’s weight is in a lower percentile, they will not necessarily be a small adult — just as longer babies do not necessarily become tall adults.
Knowing about average weights by month can help people gauge their babies’ physical development, but doctors also look for other important indicators, such as length and head circumference.
Healthcare professionals also take into account whether a baby is generally hitting other milestones on time. And by taking a detailed medical history, they can rule out any medical conditions or nutritional considerations that may be preventing a baby from gaining weight appropriately.
Weekly pregnancy weight calculator
The weight of the expectant mother is very important for the development of the fetus. It is desirable to have a normal body weight before pregnancy. Lack of weight is a serious risk factor, as a result of which a child may be born too small.
Being overweight increases the likelihood of having an oversized baby. In such situations, only a timely caesarean section made by obstetricians can help.
First trimester weight
In addition to body weight before conception, weight during pregnancy by weeks and its constant control play an important role.
In the first couple of months, it increases slowly, the baby and mother only adapt to each other. During this period, there are frequent cases of toxicosis, which additionally reduces weight. During the first trimester of pregnancy, a woman gains about 1.5 kg.
Weight in the second half of pregnancy
Intensive weight gain occurs in the second half of the term. Most women gain only 40% in the first 4 months, and the remaining 60% in the second half. However, it also happens the other way around - in some women, weight during pregnancy is gained week by week faster in the first months, there is no pathology in this.
The increase is distributed as follows:
| Fat | 28% |
| Water | 13% |
| Fruit | 27% |
| Blood | 10% |
| Uterus | 8% |
| Amniotic fluid | 6% |
| Placenta | 5% |
| Mammary glands | 3% |
Allowable weight gain
If we take the allowable weight gain for women, it is 350 g per week (50 g per day), maximum 500 g per week.
Using the weight calculator during pregnancy, you can find out what it should be at different times. To exceed this norm, it is desirable to lead an active life and monitor nutrition. Although an extra increase is undesirable, in no case should you exhaust yourself with hunger strikes. And there is nothing good in the abuse of flour products in an attempt to get to the norm either. You need to eat something that will benefit not only you, but also the child.
To obtain an accurate calculation, enter the following digital data into the pregnancy weight calculator:
- initial weight;
- growth;
- approximate gestational age in weeks.
What causes the difference in weight in different women at the same time?
The difference can be due to several reasons. One of them is age; with increasing age, the tendency to be overweight also increases. More weight is gained by women with a lack of mass before pregnancy and who have undergone early toxicosis.
The body thereby tries to compensate for the losses.
An important factor is the peculiarity of the constitution, the difference with the indications of the weight calculator during pregnancy by weeks may be due to a tendency to thinness or fullness. It also depends on the size of the baby: the larger it is, the larger the placenta will be. Sometimes a sharp increase in the appetite of the expectant mother leads to intensive weight gain, it is quite difficult to deal with it.
How is the weight gained distributed?
The normal weekly weight gain during pregnancy is as follows:
- the uterus accounts for 0.9 kg;
- adipose tissue of the order of 2.2 kg;
- the child weighs about 3.3 kg;
- tissue fluid - 2.7 kg;
- amniotic fluid approximately 1.2 kg;
- mammary glands increase by 0.5 kg
- circulating blood - per 1.2 kg.
Approximately 12.1 kg. In case of multiple pregnancy, at least 2-4 kg must be added to the figures obtained.
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Table of norms for the size of the fetus by weeks of pregnancy
The size of the child by weeks of pregnancy is the average data by which doctors monitor the development of the fetus in the tummy of the expectant mother. These figures are influenced by the genetic predisposition, the physical and emotional state of the woman.
Dimensional indicators by which changes in the fetus are determined, and where to get them
The growth of the baby in the mother's tummy, its changes in weight and length are important indicators of its development and health. By 7-8 weeks, the baby weighs about a gram. But every day it grows and gains mass. Up to 15 weeks there is a rapid mass gain, after which it slows down. From the 2nd trimester, the weekly increase is about 80 grams and from 28 to 30 weeks, the increase goes up to 300 grams per week.
There are two ways to find out the weight of a child during pregnancy - calculated and by ultrasound.
- Estimated. Before ultrasonic examination (ultrasound) was tightly included in the everyday life of doctors, the mass of the baby in the abdomen was determined by the calculation method. How they did it: the gynecologist measured the height of the fundus of the uterus and the circumference of the abdomen of the expectant mother with a centimeter tape. These values were multiplied among themselves and received the approximate weight of the baby. This method did not take into account the amount of amniotic fluid, the constitution of the mother, the genetic predisposition and the presentation of the child. This calculation method gives fairly accurate readings after the 32nd week of pregnancy. Before this period, the error of the method is up to 200 grams.
- ultrasound. Ultrasound examination is planned for each woman 3 times during pregnancy (1 time per trimester).
Unscheduled ultrasound is prescribed according to indications.
Doctors in polyclinics and antenatal clinics are guided by the data of ultrasound examinations. On ultrasound, the exact gestational age is established and the main indicators of the development of the baby in the mother's tummy are recorded.
By what indicators does an ultrasound specialist determine the intrauterine development of a child (abbreviation in English is given in brackets):
- MP (FW) - fetal weight.
- KTP (CRL) is the coccyx-parietal size. It determines the exact gestational age and size of the baby.
- BPD (BPD) is the biparietal head size.
- OFD is the distance from the frontal bone to the center of the occipital bone. According to the BPR and LZR indicators, the child's growth and development are assessed.
- DB (FL) - the length of the femur.
- OG (NS) - head circumference.
- coolant (AC) - abdominal circumference.
Changes by week (with tables): norms
To monitor the intrauterine development of the baby, doctors use the norms of the child's weight by weeks of pregnancy, which use averaged data.
| Gestational age (weeks) | Approximate length of the child, (cm) | Approximate weight of the child, (g) |
|---|---|---|
| 7 | 3 | |
| 8 | 5 | |
| 9 | 7 | |
| 10 | 9 | |
| 11 | 4.1 | 11 |
| 12 | 5.4 | 19 |
| 13 | 7.4 | 31 |
| 14 | 8.7 | 52 |
| 15 | 10.1 | 77 |
| 16 | 11.5 | 118 |
| 17 | 13 | 160 |
| 18 | 14. 2 | 217 |
| 19 | 15.3 | 270 |
| 20 | 25.8 | 345 |
| 21 | 26.7 | 410 |
| 22 | 27.8 | 506 |
| 23 | 28.9 | 607 |
| 24 | 30 | 733 |
| 25 | 34.6 | 844 |
| 26 | 35.6 | 969 |
| 27 | 36.6 | 1 135 |
| 28 | 37.6 | 1 319 |
| 29 | 38.6 | 1482 |
| 30 | 39.9 | 1636 |
| 31 | 41.1 | 1 779 |
| 32 | 42.4 | 1930 |
| 33 | 43.8 | 2088 |
| 34 | 45 | 2 248 |
| 35 | 46.2 | 2414 |
| 36 | 47. 4 | 2612 |
| 37 | 48.6 | 2 820 |
| 38 | 49.8 | 2992 |
| 39 | 50.7 | 3 170 |
| 40 | 51.2 | 3 373 |
Parents receive more accurate data on the intrauterine development of their baby by ultrasound.
First trimester
The first trimester is the period from 1 to 13 weeks. By ultrasound, the size of the fetus is estimated from 10 to 11 weeks (before this period, ultrasound is not informative).
Table of normal development of the baby in the 1st trimester according to the results of ultrasound
| Gestational age (weeks) | Height, cm | Weight, g | dB, mm | DGK, mm | BPR, mm |
|---|---|---|---|---|---|
| 11 | 6.8 | 11 | 7 | 20 | 18 |
| 12 | 8. 2 | 19 | 9 | 24 | 21 |
| 13 | 10.0 | 31 | 12 | 24 | 24 |
Second trimester
The second trimester is the 14th to 27th week of gestation.
Average fetal weight by week of pregnancy in the table (according to ultrasound results)
| Gestational age (weeks) | Height, cm | Weight, g | dB, mm | DGK, mm | BPR, mm |
|---|---|---|---|---|---|
| 14 | 12.3 | 52 | 16 | 26 | 28 |
| 15 | 14.2 | 77 | 19 | 28 | 32 |
| 16 | 16.4 | 118 | 22 | 34 | 35 |
| 17 | 18.0 | 160 | 24 | 38 | 39 |
| 18 | 20.3 | 217 | 28 | 41 | 42 |
| 19 | 22. 1 | 270 | 31 | 44 | 44 |
| 20 | 24.1 | 345 | 34 | 48 | 47 |
| 21 | 25.9 | 416 | 37 | 50 | 50 |
| 22 | 27.8 | 506 | 40 | 53 | 53 |
| 23 | 29.7 | 607 | 43 | 56 | 56 |
| 24 | 31.2 | 733 | 46 | 59 | 60 |
| 25 | 32.4 | 844 | 48 | 62 | 63 |
| 26 | 33.9 | 969 | 51 | 64 | 66 |
| 27 | 35.5 | 1 135 | 53 | 69 | 69 |
Third trimester
The third trimester is the gestation period from the 28th week.
Approximate height and weight of the child by weeks of pregnancy in the table (determined by ultrasound results)
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Is it possible to increase the weight of the fetus during pregnancy?
Let's figure out what determines the weight of the fetus during pregnancy, and how the expectant mother to correct the underweight of the crumbs:
- Nutrition. If the mother is malnourished, then the baby also receives less nutrients and slows down in development.
- Indolent diseases. If a mother has exacerbated chronic diseases during pregnancy, then her general condition can negatively affect the weight gain of the baby.
- Smoking. According to research by experts from the World Health Organization (WHO), smoking mothers increase the risk of having babies with underweight.
- Stress, emotional overload of the mother reduce her appetite, metabolic rate and overall body tone. This directly affects the absorption of nutrients by the child. The more harmonious and calmer the emotional state of a woman, the easier the gestation and intrauterine development of the child.
If the expectant mother takes care of her health, she will notice that from the 28th week her weight (and the weight of the baby) is growing rapidly. The average indicators of how much a child gains in the last weeks of pregnancy are reduced to 250 - 300 grams weekly.
Supervision by a specialist will help to keep the development of the baby under control, to ensure that it is within the normal range. If a pregnant woman develops preeclampsia, swelling, high blood pressure, the doctor will prescribe drugs and procedures that will help to go through a difficult period easier.
