J Korean Med Sci.  2016 Sep;31(9):1450-1454. 10.3346/jkms.2016.31.9.1450.

Neonatal and Infant Mortality in Korea, Japan, and the U.S.: Effect of Birth Weight Distribution and Birth Weight-Specific Mortality Rates

• Kim DH
• Jeon J
• Park CG
• Sriram S
• Lee KS

• KMID: 2468279
• DOI: http://doi.org/10.3346/jkms.2016.31.9.1450

Abstract

Difference in crude neonatal and infant mortality rates (NMR and IMR) among different countries is due to the differences in its two determinants: birth weight distribution (BWD) and birth weight-specific mortality rates (BW-SMRs). We aimed to determine impact of BWD and BW-SMRs on differences in crude NMR and IMR among Korea, Japan, and the U.S. Our study used the live birth data of the period 2009 through 2010. Crude NMR/IMR are the lowest in Japan, 1.1/2.1, compared to 1.8/3.2, in Korea, and 4.1/6.2, in the U.S., respectively. Japanese had the best BW-SMRs of all birth weight groups compared to the Koreans and the U.S. The U.S. BWD was unfavorable with very low birth weight (< 1,500 g) rate of 1.4%, compared to 0.6% in Korea, and 0.8% in Japan. If Koreans and Japanese had the same BWD as in the U.S., their crude NMR/IMR would be 3.9/6.1 for the Koreans and 1.5/2.5 for the Japanese. If both Koreans and Japanese had the same BW-SMRs as in the U.S., the crude NMR/IMR would be 2.0/3.8 for the Koreans and 2.7/5.0 for the Japanese. In conclusion, compared to the U.S., lower crude NMR or IMR in Japan is mainly attributable to its better BW-SMRs. Koreans had lower crude NMR and IMR, primarily from its favorable BWD. Comparing crude NMR or IMR among different countries should include further exploration of its two determinants, BW-SMRs reflecting medical care, and BWD reflecting socio-demographic conditions.

Keyword

Infant Mortality; Birth Weight; Korea; Japan; the United States

MeSH Terms

*Birth Weight
Databases, Factual
Humans
Infant
*Infant Mortality/ethnology
Infant, Newborn
Japan
Republic of Korea
United States

Figure

• 

  Fig. 1 Actual and expected neonatal and infant mortality rates in Korea after standardization with birth weight distribution (A) and birth weight-specific mortality rates (B) in the U.S. If Koreans had the same birth weight distribution as in the U.S., their crude neonatal and infant mortality rates would be 3.9/6.1. If Koreans had the same birth weight-specific mortality rates as in the U.S., the crude neonatal and infant mortality rates would be 2.0/3.8. *Data from the U.S. National Center for Health Statistics; †Data from the Statistics Korea (345676).

• 

  Fig. 2 Actual and expected neonatal and infant mortality rates in Japan after standardization with birth weight distribution (A) and birth weight-specific mortality rates (B) in the U.S. If Japanese had the same birth weight distribution as in the U.S., their crude neonatal and infant mortality rates would be 1.5/2.5. If Japanese had the same birth weight-specific mortality rates as in the U.S., the crude neonatal and infant mortality rates would be 2.7/5.0. *Data from the U.S. National Center for Health Statistics; †Data from Japan Ministry of Health, Labour, and Welfare (3478).

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