Early neonatal mortality, low birth weight and related factors in Japan

Objectives The author conducted an ecological study to examine prefectural differences in ENMR and the related factors in Japan, using two new indicators; birth weight (BW) adjusted ENMR and expected ENMR by BW distribution. Method Correlate analysis of data from national vital statistics and some indicators of medical care services among 47 prefectures edited by the Ministry of Health and Welfare, Japan were conducted. BW-adjusted ENMR and expected ENMR by BW, as well as other indicators, were prepared for statistical analysis. Result Crude and BW-adjusted ENMRs were significantly correlated with ENMRs for low birth weight (LBW) and very low birth weight (VLBW) early neonates (p<0.01). The number of Obstetrics and Gynecology (OB/GYN) physicians was negatively correlated with BW adjusted ENMR. Conclusion Crude and BW-adjusted ENMRs were affected mainly by LBW and VLBW early neonate specific ENMR, but not by the rate of LBW. The variation of ENMR among prefectures in Japan is attributable to the number of OB/GYN physicians. The present findings suggest that emphasis should be laid upon enhancement of regional perinatal care systems.