Average Baby Weight at Birth
The World Health Organization has established standards for infant and child growth. The average weight of a newborn is around 7 to 7 1/2 pounds (3.2 to 3.4 kg). Most full-term healthy newborns weigh anywhere from 5 pounds 11 ounces to 8 pounds 6 ounces (2.6 to 3.8 kg). Low birth weight is less than 5 pounds 8 ounces (2.5 kg) at full term, and larger than average is a birth weight over 8 pounds 13 ounces (4.0 kg). Many things can affect a newborn’s birth weight. They include:
How many weeks a pregnancy lasts: Babies born prematurely are typically smaller, and babies born past their due date may be larger. Smoking: Mothers who smoke tend to have smaller babies. Gestational diabetes: Diabetes during pregnancy can lead to a larger-than-average baby. Nutritional status: Poor nutrition during pregnancy can lead to a smaller baby, whereas excessive weight gain can lead to a larger baby. Family history: Some babies are born smaller or larger, and it may just run in the family. Gender: On average, newborn baby girls weigh a little less than boys. A multiple pregnancy: A single baby will likely have a greater birth weight than siblings born in a multiples pregnancy (twins, triplets, etc.)
Average Weight Gain in the First Year
Again, every baby differs, but here’s what you can generally expect in the first 12 months of life.
Average Baby Weight the First Two Weeks
During the first few days of life, it’s normal for both breastfed and bottle-fed newborns to lose weight. A bottle-fed baby may lose up to 5% of his body weight, and an exclusively breastfed newborn can lose up to 10%. However, within two weeks, most newborns regain all the weight they have lost and return to their birth weight.
Average Baby Weight at One Month
Most infants will gain about a pound over their birth weight by month one. At this age, infants are not as sleepy, they begin developing a regular feeding pattern, and they have a stronger suck during feedings.
Average Baby Weight at Two Months
Generally, babies will continue to gain about one pound each month into their second month of life. This usually puts them at about two to four pounds over birth weight at 2 months. The average weight at two months is about 11 pounds 4 ounces (5.1 kg) for girls and 12 pounds 5 ounces (5.6 kg) for boys.
Average Baby Weight at Six Months
On average, babies gain about one pound each month for the first six months. The average weight at six months is about 16 pounds 2 ounces (7.3 kg) for girls and 17 pounds 8 ounces (7.9 kg) for boys.
Average Baby Weight at One Year
Between six months and one year, weight gain slows down a little. Most babies double their birth weight by five to six months of age and triple it by the time they are a year old. By one year, the average weight of a baby girl is approximately 19 pounds 10 ounces (8.9 kg), with boys weighing about 21 pounds 3 ounces (9.6 kg).
Average Baby Weight Chart by Month
This growth chart is for healthy, full-term infants. A doctor may use specialized growth charts for premature babies or those born with special health needs. When it comes to weight gain, breastfed babies are less likely than formula-fed infants to gain too much weight too quickly. Breastfeeding may even help to prevent excessive weight gain and obesity. However, breastfed babies can gain too much if a breastfeeding parent has an overabundant supply of breast milk, the baby consumes excessive amounts of breast milk, or solid foods are started early.
Average Baby Length (Height)
In general, during the first six months, a baby grows about one inch per month. Between six months and one year, that growth slows down a bit to about a 1/2 inch per month. The average length of a baby boy at six months is approximately 26 1/2 inches (67.6 cm) and a baby girl is about 25 3/4 inches (65.7 cm). At one year, boys are around 29 3/4 inches (75.7 cm) and girls average 29 inches (74 cm). The factors that determine height are:
Genetics: The height of a child’s mother, father, and other family members have the most significant impact on how tall the child will be.Gender: Boys tend to be taller than girls.Nutrition: Good nutrition for both the parent during pregnancy and the baby after birth can ensure that the baby’s body gets the proper vitamins, minerals, and protein for healthy bones and optimal growth.Sleep pattern: Studies show that infants grow in length after naps and long periods of sleep.Physical activity: Body movement and physical activity help build strong muscles and bones.Overall health: Chronic illness and disease during childhood can affect growth and development.
Average Baby Length Chart by Month
This chart shows the average length or height of healthy, full-term babies from one month to one year. Growth spurts can happen at any time, and they do not necessarily follow a pattern. Some of the ages that your child may experience a growth spurt are at ten days, three weeks, six weeks, three months, and six months. During and after a growth spurt, your baby will need more milk. You may need to feed your baby as much as every hour or two, a phenomenon often referred to as cluster feeding. This tends to happen more often with breastfed babies. Since breast milk is made based on supply and demand, your baby will breastfeed much more often around the time of a growth spurt, signaling your body to make more milk. Luckily, these frequent feedings only last about a day or two as your milk supply adjusts to your growing baby’s needs. After that, your child should settle back down into a more regular feeding routine.
Baby Growth Chart Considerations
Growth charts and percentiles are just tools that help track the growth of children over time. The 50th percentile means average, not “normal.” While some children fall on the average line, many children fall below or above it. So, if your baby is not in the 50th percentile, it doesn’t mean that they are not growing at a healthy rate. Healthy infants can be in the 5th percentile as well as the 95th percentile. While it may be tempting to compare your child’s growth and development to other children, it is important to remember that babies come in all shapes and sizes.
Not All Growth Charts Are Equal
Just as all children are different, it is important to realize that not all growth charts are the same. The Centers for Disease Control and Prevention (CDC) provides a set of growth charts that include older data and information from a combination of feeding methods. The CDC growth charts are a reference and show how children grew during a specific period in the United States. The World Health Organization (WHO) growth charts contain more data from breastfed babies. Mothers are breastfeeding more and more and the WHO charts are considered a standard on how children should grow. The CDC recommends using the WHO growth charts for all babies (whether they are breastfeeding or taking formula) during the first two years. The American Academy of Pediatrics (APP) agrees with the CDC recommendation.
A Word From Verywell
When you compare your child to other babies, you may worry if you notice that they are smaller or heavier than their peers. Luckily, there is an easy way to ease your fears and find out for sure if your child is growing as expected. You just have to follow the regular schedule for well-child visits that your healthcare provider gives you. The doctor will weigh and measure your baby each time you see them. And, they will keep track of your child’s growth and overall health over time. Often, their growth will be well within the expected range since their last visit. If not, these checkups allow the doctor to notice any diversions from your child’s anticipated growth and address any possible concerns quickly, if applicable. There was an error. Please try again.
