Low birth weight, very low birth weight rates and gestational age-specific birth weight distribution of Korea newborn infant

To obtain the low birth weight (LBW) rate, the very low birth weight (VLBW) rate, and gestational age (GA)-specific birth weight distribution based on a large population in Korea, we collected and analyzed the birth data of 108,486 live births with GA greater than 23 weeks for 1 yr from 1 January to 31 December 2001, from 75 hospitals and clinics located in Korea. These data included birth weight, GA, gender of the infants, delivery type, maternal age, and the presence of multiple pregnancy. The mean birth weight and GA of a crude population are 3,188 +/- 518 g and 38.7 +/- 2.1 weeks, respectively. The LBW and the VLBW rates are 7.2% and 1.4%, respectively. The preterm birth rate (less than 37 completed weeks of gestation) is 8.4% and the very preterm birth rate (less than 32 completed weeks of gestation) is 0.7%. The mean birth weights for female infants, multiple births, and births delivered by cesarean section were lower than those for male, singletons, and births delivered vaginally. The risk of delivering LBW or VLBW infant was higher for the teenagers and the older women (aged 35 yr and more). We have also obtained the percentile distribution of GA-specific birth weight in infants over 23 weeks of gestation.