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

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.

Age at menarche in the Korean female: secular trends and relationship to adulthood body mass index

PURPOSE: The objective of this study is to estimate the trend in age at menarche in the Korean female and evaluate the relationship between age at menarche and adult body mass index (BMI), which is a indicator of later-life health. METHODS: We conducted a cross-sectional analysis of a nationally representative sample (self-reported age at menarche and measured height and weight) of 11,065 females aged 15 and older. Data were obtained from the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV, 2007-2009). RESULTS: We found a statistically significant decline in age at menarche in successive birth groups, indicating a 0.726 year decrease per decade. The age at menarche in 1990-1994 year birth group was 12.60 years, which showed a significant decreased from 3.11 years in the 1980-1984 birth group. We also found a significant negative association between age at menarche and current BMI. A one-year decrease in age at menarche was associated with mean BMI increase of 0.109 kg/m2 (95% confidence interval [CI], 0.069 to 0.150) after adjustment for age. In multivariate logistic regression, the odds ratios of obesity in females with early menarche (<12 years) was 1.845 fold (95% CI, 1.441 to 2.361). CONCLUSION: We found that age at menarche is still falling in the Korean female. We also found that early menarche is a risk factor for obesity in adults.

Age at menarche in the Korean female: secular trends and relationship to adulthood body mass index

PURPOSE: The objective of this study is to estimate the trend in age at menarche in the Korean female and evaluate the relationship between age at menarche and adult body mass index (BMI), which is a indicator of later-life health. METHODS: We conducted a cross-sectional analysis of a nationally representative sample (self-reported age at menarche and measured height and weight) of 11,065 females aged 15 and older. Data were obtained from the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV, 2007-2009). RESULTS: We found a statistically significant decline in age at menarche in successive birth groups, indicating a 0.726 year decrease per decade. The age at menarche in 1990-1994 year birth group was 12.60 years, which showed a significant decreased from 3.11 years in the 1980-1984 birth group. We also found a significant negative association between age at menarche and current BMI. A one-year decrease in age at menarche was associated with mean BMI increase of 0.109 kg/m2 (95% confidence interval [CI], 0.069 to 0.150) after adjustment for age. In multivariate logistic regression, the odds ratios of obesity in females with early menarche (<12 years) was 1.845 fold (95% CI, 1.441 to 2.361). CONCLUSION: We found that age at menarche is still falling in the Korean female. We also found that early menarche is a risk factor for obesity in adults.

Bone Mineral Density Reference of 10-20 year-old Korean Children and Adolescents: Based on Hologic DXA from the Korean National Health and Nutrition Examination Surveys / 대한소아내분비학회지

PURPOSE: To obtain normative data on bone mineral density of each region of interest (ROI) measured by Hologic model dual-energy x-ray absorptiometry (DXA) of children and adolescents. METHODS: Cross sectional results from 723 healthy Korean children and adolescents (10-20 years of age) in the Korean National Health and Nutrition Examination Surveys were analyzed. We used age- and sex-specific reference data for bone mineral density (BMD) of the lumbar spine, femur neck, and total body except head from Hologic DXA device as recommended by the International Society for Clinical Densitometry. RESULTS: The bone mineral density of each ROI increased with age in both boys and girls. Maximal increase in the lumbar BMD occurred between ages 11 and 12 in girls and between ages 12 and 14 in boys. However, the increases of BMD in each ROI were different. The plateaus of the lumbar spine and whole body except head BMD in girls occurred at ages 15 and 17, respectively. The plateaus of BMD in each ROI occurred at age 17 in boys. CONCLUSION: Most of the skeletal mass, including lumbar spine and total body except head, is reached before the end of the second decade. This study provides reference values for bone density of each ROI measured with DXA for children and adolescents.