Secular Changes in the Mean Birth Weight in Japan On the Single Births, by Prefecture and Region

• Published in: Nippon Eiseigaku Zasshi (Japanese Journal of Hygiene) Vol. 32; no. 5; pp. 650 - 659
• Main Authors: Kahyo, Hiroaki, Doi, Toru, Higa, Keiko, Ohsawa, Susumu
• Format: Journal Article
• Language: English
• Published: The Japanese Society for Hygiene 1977
• ISSN: 0021-5082; 1882-6482
• DOI: 10.1265/jjh.32.650

In this study we investigated the secular trends in the mean birth weight of the single births by prefecture and region, using the vital statistics of the Japanese government, and then compared the mean birth weight of single births with that of total births (including the single and multiple births) reported in the previous paper (Ref. 1). The mean birth weights and their standard deviations of each available year (1969-74) were computed by sex and by prefecture and region (Table 1∼2). The ranges, the means and their standard deviations of the differences between the mean birth weight of single births and that of total births in each year were computed by sex, by prefecture and region (Table 3). During this period the ranges of the former differences were 8gm. at the prefectural level, 4gm. at the regional level when both sexes are combined. The means of the differences were almost constant, with 8gm. in males, and 8-9gm. in females at the two areal levels and the standard deviations of the differences were very small, 1.1-1.7gm. at the prefectural level and 0.5-1.2gm. at the regional level. All other results presented in Table 1∼7 and in Fig. 1∼2 showed quite similar patterns in comparison with those of total births reported previously. In conclusion we wish to emphasize that it would be possible, at least at the prefectural and regional level, to assess the secular trends of the mean birth weight of the single births from the data of the total births quite accurately, taking into consideration the constant differences of 8gm. in males, and 8-9gm. in females.