SEASONALITY OF PRETERM BIRTHS IN JAPAN
SEASONALITY OF PRETERM BIRTHS IN JAPAN
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DOI：
10.1093/ije/21.1.91
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发表时间：
1992-02-01
影响因子：
7.7
通讯作者：
KAHYO, H
中科院分区：
文献类型：
--
作者：
MATSUDA, S;KAHYO, H
使用传统的时间序列分析方法分析了1979年1月至1983年12月日本早产比例的季节变化，该方法将序列中的变化分为趋势、季节变化、其他周期变化和剩余的不规则波动。 结果表明，日本的早产率具有明显的季节性周期性，夏季和冬季有两个高峰，按妊娠期分析的季节性特征表明，夏季和冬季在峰度和偏度上存在着有趣的差异，即夏季早产率的增加具有偏度增加的特征，这意味着分布的下半部分得到了扩展。 另一方面，冬季增加的特点是峰度下降，对应于一个平顶分布。 这一结果表明，两个季节之间早产的原因可能不同。根据这一时期日本的实际出生数据，进行了理论模拟，以研究怀孕季节如何影响早产比例的季节变化。 结果表明，至少对于第一胎来说，受孕率的季节性可以解释早产比例的季节性变化。另一项分析表明，在日本，5月和6月受孕更容易导致早产。
Seasonal variations in the proportion of preterm births in Japan from January 1979 to December 1983 are analysed using a traditional method of time-series analysis, which divides the variation in a series into trend, seasonal variation, other cyclic change, and remaining irregular fluctuations. It is shown that the proportion of preterm births in Japan have a clear seasonal periodicity with two peaks in summer and winter.Analysis of seasonality by period of gestation shows that interesting differences in kurtosis and skewness exist between summer and winter, i.e. the summer increase in preterm births was characterized by an increase of skewness which means an extension of the lower part of the distribution. On the other hand, the winter increase was characterized by a decrease of kurtosis which corresponds to a flat-topped distribution. This result suggests that causes of preterm births might be different between the two seasons.Theoretical simulations based on actual birth data in Japan over the period, are carried out to examine how season of conception could influence seasonal variations in the proportion of preterm births. Results show that, at least for first births, seasonality in conception rates could be one explanatory factor for the observed seasonal variation in proportions of preterm births.Another analysis reveals that conception in May and June are more likely to result in preterm births in Japan.