Average Baby Weight at Birth

Babies born at a healthy weight have a lower risk for health problems. According to the Centers for Disease Control and Prevention, low birthweight babies are at a greater risk for developing problems such as neurodevelopmental handicaps or respiratory tract conditions. The CDC also notes that high birthweight babies have an increased risk for birth injuries and infant mortality compared with normal-weight infants.

The Big and Small of the Matter

Infants can be born at a normal healthy weight; low birth weight, or small for gestational age; or large for gestational age. Newborns weighing less than 5 Ibs. 8 oz. are considered low-birth weight babies, according to the March of Dimes. The CDC notes that babies born at or above the 90th percentile are considered large-for-gestational-age, or LGA, and that approximately 9 percent of babies born in the United States in 2005 were LGA babies.

Right in the Middle

Close-up of a newborn baby

How Much Should a Baby Weigh at 4 Months?

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A baby considered a normal or healthy weight at birth weighs at least 5 Ibs. 8 oz. According to the Nemours Foundation, most babies born full term weigh between 6 Ibs. 2 oz. and 9 Ibs. 2 oz. Babies are considered full-term when they’re born between 37 and 40 weeks' gestation. Infant growth charts can help gauge how your baby’s weight compares with other newborns of the same gender. Babies born at the 50th percentile are considered about average compared with other newborns. The 50th percentile for birth weight according to CDC growth charts is approximately 8 Ibs. for boys and 7 1/2 Ibs. for girls. Longer babies are expected to weigh more.


Infants weighing below or above the recommended weight range at birth are at risk for certain health problems. According to the March of Dimes, low-birth-weight infants have an increased risk for respiratory, heart, vision or intestinal problems, bleeding in the brain, disabilities or death. Babies born large for gestational age are at risk for injury at birth, low blood sugars and complications related to low blood sugars, according to the National Institutes of Health. The CDC notes that LGA babies are at risk for becoming obese later in life.


Close-up of a newborn baby

The Size of a Newborn Baby

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If you’re pregnant, you can increase your chances of delivering a normal, healthy-weight newborn. According to the March of Dimes, avoiding tobacco smoke, receiving regular prenatal care, taking at least 400 mcg of folic acid per day and avoiding chronic health conditions such as diabetes or high blood pressure can help prevent a low-birth weight baby. KidsHealth recommends women avoid tobacco, alcohol or other drugs and eat a nutritious diet during pregnancy to increase the chance of delivering a healthy-weight baby.

Other Factors

In addition to maternal lifestyle during pregnancy, other factors can affect the size of a baby at birth. These include:

  • the length of gestation
  • birth order
  • the presence of medical problems
  • gender
  • the size of the parents
  • multiple births
  • according to KidsHealth