How Much Should My Unborn Baby Weigh?

Infant weight is one factor in determining newborn health.

Healthy Birth Weight

Your unborn baby can gain as much as 1 pound per week in the ninth month of pregnancy. Typically a baby weighs about 3-1/2 to 4 pounds as it enters the 36th week. According to the National Center for Health Statistics, the average U.S. healthy, full-term newborn weighs between 6 and 8 pounds.

The Very Small or Large Baby

Babies who are significantly smaller than average may have congenital or malabsorption issues. Babies who are significantly larger may have diabetic or obese mothers and these babies are at higher risk for obesity. In either case, babies on either end of the weight curve are often less healthy at birth and may have long-term health issues.

Bottom Line

Mothers who eat a nutritious diet and follow pregnancy guidelines are more likely to have healthy babies. Routine prenatal care may be able to identify and correct problems that lead to very small or very large babies.

References

• The Physics Factbook: Mass of a Newborn Baby
• American Pregnancy Association: Monitoring Your Newborn's Weight Gain
• ACJN: Variation in Newborn Size