Average Infant Growth from Birth to One Year

Height, Weight, and Growth Spurts: What's Normal and Average?

Hispanic baby girl sitting on a scale
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Like many parents, you might be wondering if your baby is growing normally. However, despite the temptation, it's not recommended to compare your child's growth and development to other children. Every child is an individual and grows at his or her own pace. Some kids are big, and some kids are small. There's definitely a range of healthy growth. And, since growth depends on many factors, not everyone follows the same pattern of growth.

Here are some of the averages for weight and height during the first year. But, remember, if your child is a little smaller or a little bigger than these average measurements, it's still normal. 

What Growth Charts Mean

Growth charts and percentiles are just tools that help track the growth of children over time. The 50th percentile doesn't mean normal. The 50th percentile means average. While some children fall on the average line, many children fall below or above that 50 percent line. So, if your baby is not in the 50th percentile, it certainly doesn't mean that he or she is not growing at a healthy rate. Many factors contribute to your baby's height and weight, including genetics, diet, and activity level. Normal, healthy infants are in the 5th percentile as well as the 95th percentile.

Average Weight of a Baby in First Year

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% or his body weight, and an exclusively breastfed newborn can lose up to 10% of his or her body weight. But, within two weeks, most newborns regain all the weight they have lost and return to their birth weight.

By one month, most infants will gain about a pound over their birth weight.

At this age, infants are not as sleepy, they begin developing a regular feeding pattern, and they have a stronger suck during feedings.

On average, babies gain about one pound each month until they are six months old. Most babies double their birth weight by five months of age and triple their birth weight by the time they're one year old. The average weight of a 6-month-old is about 16 pounds (7.3 kg), and the average weight of a 1-year-old is approximately 21½ pounds (9.8 kg). Boys may be bigger than girls, and breastfed infants may weigh less than formula-fed babies.

Average Height of a Baby in First Year

In general, during the first six months, a baby grows about one inch per month. Between 6 months and one year, it slows down a bit to about a ½ inch per month. The average height of a child at six months is approximately 25 ½ inches (65 cm), and the average height of 1 year old is around 29 inches (74 cm).

Weight Loss and Gain in Babies

As mentioned above, it's normal for a newborn to lose weight during the first few days of life. But, after that period, weight loss or poor weight gain in a child is a sign of a problem. For breastfed babies, it could mean that the baby is not getting enough breast milk.

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. But, breastfed babies can gain too much if a mother has an overabundant supply of breast milk, the child spends too much time nursing or starts solid foods early.

Baby Growth Spurts

Infants don't grow at a consistent rate. They have times when they grow slowly and times when they shoot up all of a sudden. When they have a big surge of growth in a short amount of time, it's called a growth spurt. Growth spurts can happen at any time, and they don't 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 breast milk. Since breast milk is made based on supply and demand, your baby will breastfeed much more often during these times. You may need to breastfeed your baby as much as every hour or two. This increase in breastfeeding tells 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.

A Word from Verywell

Children are individuals. They grow at different rates. It's difficult to compare one child to another, even their own brothers and sisters. When you look around at other children, it can be scary if you think your child is smaller than he should be or he weighs more than he should for his age. So, the best way to ease your fears and be sure that your child is gaining weight and growing healthy and strong is to take her to your health care provider for her well-child visits. Once your baby is born, you should receive instructions for follow-up care for both you and your child. If you don't, then ask.

You'll probably bring your baby to the doctor or clinic for the first time within a week of your baby's birth, and then at regular intervals after that. Your child's healthcare provider will weigh and measure your baby, and keep track of your little one's growth and overall health over time. This way, you can feel confident that your child is growing at a normal, healthy rate. And, if there are any issues or concerns, they can be noticed and taken care of right away. 

Sources:

Eidelman AI. Breastfeeding and the use of human milk: an analysis of the American Academy of Pediatrics 2012 Breastfeeding Policy Statement. Breastfeeding Medicine. 2012 Oct 1;7(5):323-4.

De Onis, M. WHO child growth standards: length/height-for-age, weight-for-age, weight-for-length, weight-for-height and body mass index-for-age. WHO. 2006.

Lawrence, Ruth A., MD, Lawrence, Robert M., MD. Breastfeeding A Guide For The Medical Profession Eighth Edition. Elsevier Health Sciences. 2015.

Riordan, J., and Wambach, K. Breastfeeding and Human Lactation Fourth Edition. Jones and Bartlett Learning. 2014.

Savino F, Liguori SA, Fissore MF, Oggero R. Breast milk hormones and their protective effect on obesity. International journal of pediatric endocrinology. 2009 Nov 4;2009(1):1.

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