As weight is easier to determine than gestational age , the ORGANIZATION@1 tracks rates of low birth weight -LRB- WHO | Data and statistics It is estimated that one-third of these low birth weight deliveries are due to preterm delivery .

For this reason , the ORGANIZATION@1 tracks rates of low birth weight instead . WHO | Data and statistics It is estimated that one-third of these low birth weight deliveries are due to premature delivery .
