The Centers for Disease Control and Prevention and the World Health Organization recommend using growth charts based on breastfed babies to gauge the normal growth rate for all infants. The WHO charts are used for breastfed and formula-fed infants from birth to 2 years of age.
How Infant Growth Charts Are Used
Infant growth charts are used by your pediatrician during well-baby checkups to determine if your baby is growing normally. Your baby will be weighed and his weight and age will be plotted on an infant growth chart for each of his checkups to produce a growth curve. The growth curve will be compared to age- and sex-matched growth curves that range from the 3rd to 97th percentile of normal infant growth. For example, if your baby’s weight is at the 30th percentile, this means he weighs more than 30 percent of infants of his age and sex. Your baby should maintain roughly the same percentile in his growth curve over time.
Normal Infant Weight Range
Based on the 3rd to 97th percentile range from the 2006 WHO growth charts, the typical weight of a 4-month-old boy is 12 lbs 6 oz to 18 lbs 15 oz. A 4-month-old girl normally weighs 11 lbs 4 oz to 17 lbs 14 oz. A 5-month-old baby boy should weigh 13 lbs 7 oz to 20 lbs 5 oz, and a girl of the same age should weigh 12 lbs 2 oz to 19 lbs 3 oz. Based on a 2010 study published in "Pediatrics," if your baby was born prematurely -- at less than 37 weeks -- alternate growth charts are used to determine whether your baby is growing and gaining weight until she catches up. Talk with your baby's doctor if you are concerned about her weight gain.
- Centers for Disease Control and Prevention: WHO Growth Charts
- World Health Organization: The WHO Multicentre Growth Reference Study
- World Health Organization: Child Growth Standards, Weight-for-age, Simplified Field Table, Boys Percentiles
- World Health Organization: Child Growth Standards, Weight-for-age, Simplified Field Table, Girls Percentiles
- Pediatrics: New Intrauterine Growth Curves Based on United States Data