Korean reference for full-term birth length by sex: data from the 4th Korean National Health and Nutrition Examination Survey (KNHANES-IV; 2007–2009)

PURPOSE: The purpose of this study was to construct reference data for birth length of full-term and preterm Korean infants by sex and to define a sex-specific birth length cut-off to identify small for gestational age (SGA). METHODS: Data were collected from the 4th Korean National Health and Nutrition Examination Survey (2007–2009), comprising 843 children with birth length data and birth history. RESULTS: References for the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles of birth length and weight were created using singleton neonates of gestational age (GA) 36–37 weeks and 38–41 weeks by sex. The birth length cutoff value for SGA (<10th percentile) was 48 cm in both male and female neonates, and the ≤3rd percentile cutoff was 47 cm in males and 46 cm in females born at a GA of 38–41 weeks. CONCLUSIONS: New Korean reference data were created for birth length and differed from those of other ethnicities. Further research on short-term and long-term health outcomes of SGA infants based on the new reference data is needed.