March of Dimes March of Dimes Peristats

Calculations

Birthweight

Birthweight rates are stratified into three categories: very low birthweight (less than 1500 grams or 3 1/3 pounds), low birthweight (less than 2500 grams or 5 1/2 pounds, includes very low birthweight) and not low birthweight (2500 grams or greater). Calculations are based on the number of live births to infants in a specific birthweight category divided by all live births, less the not-stated values multiplied by 100. Low birthweight and very low birthweight rates among singletons and multiples are calculated the same way.