When a baby is born, one of the most important indicators of good health is weight.
Why does weight matter?
One of the first things a doctor will record right after a baby’s birth is their weight. A baby who is too light or too heavy may need to be further examined by a doctor to ensure they have no underlying health problems, such as an infection or a systemic disease.
How to measure a baby’s weight?
A baby can be measured at home using a normal electronic scale, with the assistance of two adults. Assign one adult to stand on the scale and another adult to hold the baby. The adult standing on the scale should stand still and wait until their weight appears on the display panel — say 60.5 kg. After the weight is recorded, the adult holding the baby then the baby to the adult standing on the scale. The new weight is recorded. To get the baby’s weight, subtract the initial weight from the new weight — say 64.0 minus 60.5 = 3.5.
Note that babies should be weighed naked, so be sure to undress the child before starting this procedure.
How much should a healthy newborn weigh?
The average birth weight for a full-term baby is between 2.5 kg and 4.5 kg, depending on the mother’s ethnicity and size. Babies will gradually lose around 225 grams of weight within the first 5 days, and by the 10th day of life, they will regain all of that. During the first month, a healthy baby will usually gain 100-225 grams per week. A firstborn is usually smaller than their later siblings, and boys are, on average, a bit bigger than girls.
What to do if my child weighs too little?
A full-term baby is considered small if their birth weight is less than 2.5 kg. This is more common among parents who are, themselves, small and mothers who are pregnant with twins. It is also seen in premature babies or babies who experienced complications inside the womb.
Some small babies may need extra medical care after birth. Apart from that, they usually catch up naturally just by drinking lots of breast milk or infant formula and by eating lots of quality foods when they’ve reached 6 months of age. Talk to Your Child’s pediatric doctors if you are concerned or if the little one continues to be in the 97th percentile of smallest children.
What if my child weighs way more than average?
Most times, big babies are healthy. They are big simply because their parents or grandparents are big, or because they arrived well after their natural due date.
The most common medical reason for big babies is macrosomia, which is often a complication of gestational diabetes. Babies with macrosomia often weigh more than 4.5 kg at birth. This is more likely to happen to women who were overweight at the start of pregnancy, even if they did not develop gestational diabetes.
A baby diagnosed with fetal macrosomia is more likely to be born with a blood sugar level that’s lower than normal and may also be at risk for childhood obesity.
Our data and information are based on information from the World Health Organisation and based on global averages of full-term infants who are born at 37 weeks or later.
The graphs we show are based on a child’s sex. If the sex was set as “unknown”, we use growth charts of female babies.
Premature babies are monitored via a different growth chart specifically designed for babies born during the gestational ages of 25-36 weeks. See the sources below for more information.
Dr. Piyawut Kreetapirom, MD. (30 March 2021)
- Thai Growth Chart, Society of Pediatric Nutrition of Thailand
- Weight for age, The WHO
- Your Newborn's Growth, Kid's Health
- Job-Aid, Weighing and Measuring a Child, The WHO
- Newborn Measurements, Stanford Children's Health
- Physical Growth in Newborns, Michigan Medicine
- Having a Small Baby, Pregnancy Birth Babies
- Low Birthweight, March of Dimes
- Excess Weight, Diabetes Raise Risk of Bigger Babies, WebMD
- What Is So Bad About A Big Baby?, Diabetes Journal
- Fetal Macrosomia, Mayo Clinic