New Korean reference for birth weight by gestational age and sex: data from the Korean Statistical Information Service (2008-2012)

Abstract

Purpose: To construct new Korean reference curves for birth weight by sex and gestational age using contemporary Korean birth weight data and to compare them with the Lubchenco and the 2010 United States (US) intrauterine growth curves.

Methods: Data of 2,336,727 newborns by the Korean Statistical Information Service (2008-2012) were used. Smoothed percentile curves were created by the Lambda Mu Sigma method using subsample of singleton. The new Korean reference curves were compared with the Lubchenco and the 2010 US intrauterine growth curves.

Results: Reference of the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles birth weight by gestational age were made using 2,249,804 (male, 1,159,070) singleton newborns with gestational age 23-43 weeks. Separate birth weight curves were constructed for male and female. The Korean reference curves are similar to the 2010 US intrauterine growth curves. However, the cutoff values for small for gestational age (<10th percentile) of the new Korean curves differed from those of the Lubchenco curves for each gestational age. The Lubchenco curves underestimated the percentage of infants who were born small for gestational age.

Conclusion: The new Korean reference curves for birth weight show a different pattern from the Lubchenco curves, which were made from white neonates more than 60 years ago. Further research on short-term and long-term health outcomes of small for gestational age babies based on the new Korean reference data is needed.

Keywords: Birth weight; Gestational age; Growth charts; Koreans; Small for gestational age infant.

Fig. 1

The new Korean birth weight curves for male (A) and female (B) newborns.

Fig. 2

The new Korean birth weight curves (black solid line) compared with the 2010 United States intrauterine growth curves (red dashed line) for male (A) and female (B) newborns/Lubchenco curves (blue dashed line) for male (C) and female (D) newborns. The line represents 10th, 50th, and 90th birth percentile, respectively.