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. Conclusion: 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.