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Baby Birth Weight Statistics

Growth and Development

By

Updated May 16, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Average Birth Weight

The mean or average birth weight in the United States is about 3,389g or 7 lb, 7.5 oz. However, any birth weight of a term newborn between 5 lbs, 8 oz and 8 lbs, 13 oz is considered to be normal.

Baby Birth Weight Statistics

Although most babies are born between 3,000g (6 lbs, 9 oz) and 3,499g (7 lbs, 11oz), there is a broad range of sizes for the 4 million babies born each year- ranging from just under 1 pound to more than 16 pounds. The smallest babies are typically the most premature.

  • 61,773 births - 1499g or less (3.3 pounds or less)
  • 67,140 births - 1500g to 1999g (3.3 to 4.4 pounds)
  • 218,296 births - 2000g to 2499g (4.4 to 5.5 pounds)
  • 788,148 births - 2500g to 2999g (5.5 to 6.6 pounds)
  • 1,663,512 births - 3000g to 3499g (6.6 to 7.7 pounds)
  • 1,120,642 births - 3500g to 3999g (7.7 to 8.8 pounds)
  • 280,270 births - 4000g to 4499g (8.8 to 9.9 pounds)
  • 39,109 births - 4500g to 4999g (9.9 to 11 pounds)
  • 4,443 births - 5000g to 8165g (11 to 18 pounds)

Baby Birth Weight Trends

It is well known that kids are getting bigger, with the childhood obesity epidemic continuing to be a problem. And some experts now think that some of the obesity problem can start as early as the newborn period. So are newborn babies getting bigger, too?

The average birth weight actually went down from 7 lbs, 9 oz to about 7 lbs, 7 oz.

  • average birth weight in 1990 - 3,441g
  • average birth weight in 1995 - 3,435g
  • average birth weight in 2000 - 3,429g
  • average birth weight in 2005 - 3,389g

As you can see, statistics show that babies are actually getting a little smaller, and this is not thought to be due to more premature babies or other independent factors.

Newborn Weight Classifications

Depending on their weight at birth and their gestational age, using special growth charts, babies are typically classified as being:

  • Small for gestational age (SGA) - birth weight less than the 10th percentile

  • Appropriate for gestational age (AGA) - normal birth weight

  • Large for gestational age (LGA) - birth weight greater than the 90th percentile

  • Intrauterine Growth Restriction (IUGR) - lower birth weight than expected for a baby's gestational age

  • Extremely low birthweight (ELBW) - infants with a birthweight less than 1000 grams or 2.2 pounds

  • Very low birthweight (VLBW) - infants with a birthweight less than 1500 grams or 3.3 pounds

  • Low birthweight (LBW) - infants with a birthweight less than 2500 grams or 5.5 pounds

  • Normal birthweight - between 5 lbs, 8 oz and 8 lbs, 13 oz

  • High birthweight (HBW) - infants with a birthweight of more than 4000g or 8.8 pounds

Why all of the different classifications? Many can be used together. For example, a premature baby could be born low birthweight or every extremely low birthweight, but still be at an appropriate weight for his gestational age.

On the other hand, a full-term baby who was born at 2,500g (5.5 pounds) would likely be classified as being both SGA and IUGR.



Sources:

CDC. VitalStats. Births. 2008 Birth Data.

Donahue, S M. Trends in birth weight and gestational length among singleton term births in the United States: 1990-2005. Obstetrics & Gynecology. Volume: 115 Issue: 2 Pt 1 (2010-02-01) p. 357-64.

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