The average length for a newborn is 19 to 20 inches (in) (48.2 to 50.8 centimeters [cm]) from the top of the head to the heel of the foot, but this can vary. Doctors also consider a range of 18.5 to 20.9 in (47 to 53 cm) to be typical.
Most newborn babies follow a predictable level of growth during their first year. People can track the length of their baby using average growth charts.
This article looks at the average baby length, month-by-month, for the first year of life. We also discuss what it means when a baby is shorter or longer than average and when to speak with a doctor.
The World Health Organization (WHO) publishes standard infant growth charts according to the expected growth of children in
It is important to note that most people use the terms “length” and “height” interchangeably. However, until the age of
In measurement terms, experts call this recumbent length. This is different from height, which doctors will measure when a child is able to stand.
The above numbers represent averages. Children can be healthy at a wide range of heights.
A parent or caregiver who takes their baby in for measuring should also know that an infant’s measured length can vary according to who is doing the measuring and how much the baby is moving around at the time.
Therefore, if it seems there is an unexpected change in a baby’s length from one visit to the next, it can be due to differences in measuring. A person may wish to request another measurement during the visit or at the next one to rule out a legitimate issue.
There is a wide variation in typical birth weights and lengths for babies. Some babies are smaller or larger than others and have no health problems. For this reason, length alone does not reveal whether a baby is healthy.
Instead, doctors look at the overall growth pattern over time. Growth rates for length are fairly predictable among healthy babies. If a baby is born longer than average, they are likely to stay this way as they grow.
But if a baby that is significantly smaller or larger than is usual, or changes in size in an unexpected way, it may indicate a genetic difference or health condition.
A child who falls below the 5th percentile for length may display an atypical growth pattern. By the age of 12 months, a length of
An insufficient growth in length, but not weight, in the first year of life is uncommon and may be due to a genetic or other underlying condition.
Many factors affect the length of babies. One of the most influential is genetics. A 2018 study notes that genetics have a stronger association with birth length than with birth weight.
Other factors that may cause a smaller size in a newborn include:
After birth, factors that may affect infant growth include:
- Nutrition: Getting enough milk or formula helps babies gain weight, which helps them grow.
- Hormones: Some children with hormonal imbalances can grow slowly or more quickly than their peers.
- Medications: Some medications, such as steroids,
may reduce growth. - Genetics: Children are likely to grow to be a similar height to their birth parents.
Sometimes, the effects of these factors only become apparent later on, and people may not notice them in the first year of life.
However, doctors’ individual recommendations may vary slightly. In general, a pediatrician will want to examine the baby when they are:
- 3 to 5 days old
- 1 month old
- 2 months old
- 4 months old
- 6 months old
- 9 months old
But a healthcare professional may recommend more frequent visits for a baby who loses a lot of weight after birth or has an unusual growth pattern.
Parents and caregivers also should not wait if they have concerns before contacting a doctor.
In the early weeks of life, it can be difficult for parents or caregivers to know how much to feed a newborn. If the baby loses weight after birth, there could be feelings of pressure to help them regain the weight as quickly as possible, especially if the infant was born prematurely or has other health risk factors.
However, the amount of food newborns eat affects their weight
How much should breastfed babies eat?
Most breastfed newborns eat every
Since a nursing person cannot measure how much milk they are giving the baby, they can gauge whether the baby is getting enough milk by looking at the frequency of nursing and diaper changes. These indicators include the following:
- The baby is nursing at least 8 to 12 times in 24 hours
- By day 2, the baby should have at least two wet diapers in 24 hours. By day days 3 and 4, at least three or more wet diapers, and by day 5, at least six or more wet diapers.
- By day 4, at least 3 to 5 bowel movements a day.
- The baby is gaining weight.
How much should formula-fed babies eat?
During the first few days of life, people typically start by offering formula-fed babies
Similarly to breastfed newborns, formula-fed infants should eat 8 to 12 times in 24 hours, including at night. As they grow, their belly grows, and so they may drink more with each feeding. This means feeds may get further apart.
This will continue until they are approximately 6 months old when the child is ready to begin eating solid foods.
As with adults, babies are unique. As long as the infant is growing typically and does not suddenly fall well below their previous growth percentile, this is usually a good sign.
Before the age of
Caregivers should know that at this stage, doctors may switch from the WHO growth charts to the CDC’s growth reference charts.
Since standing height measures slightly less than recumbent length, a child’s classification may change slightly at this point. The pediatrician can help parents and caregivers answer questions about length, growth, nutrition, and more.
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