Analysing the seasonality of births in mainland China

The seasonality of human births varies in different countries and regions. Explanations for this variation have been divided into biological and behavioural factors. This paper documents birth seasonality in mainland China using data for a large sample from China's Fifth National Population Census (FNPC) conducted in 2000. The main method used was the decomposition of monthly time series birth data into annual, seasonal and random trends. The results show large seasonal birth fluctuations, with a salient peak of October births. The study hypothesis is that this seasonal birth pattern is partially due to a home-bound wave of movement of people after the annual Spring Festival. Subsequent analysis of the calculated de-trended monthly births provided supportive evidence for this hypothesis. Further in-depth analysis showed that the magnitude of births varied with location and family characteristics. This result should inform researchers in the field of economics, where seasonality of births has been previously regarded as exogenous.