Which month to give a birth? The analysis on birth seasonality of China

Abstract

A series of medical and biological studies have identified a strong link between the season during which a child is born and early childhood development and adult health. While providing an explanation for the seasonal determinants of birth remains one of the key challenges for demographers, understanding seasonal birth peaks and troughs can inform both public health planning and efforts to prevent childhood diseases. The seasonality of births varies across and within countries. Nonetheless, there has been scant research into the seasonality of births in China. This study takes an in depth look at the seasonal fluctuations in China’s births since 1960 and investigates the effects on seasonality of several key factors such as parity, residence (urban or rural area), and changes to fertility policies. Traditionally, winter has been the peak season of births in China, while spring and summer have been lean seasons, a pattern which is quite different than patterns in Europe and the United States. After 1990, the sweeping implementation of one-child policy and the wider use of modern contraceptives among Chinese women prompted a fundamental shift in the seasonality of births, with the deviation of births from month to month gradually diminishing over time. People's self-control may serve as a key determinant accounting for such seasonal changes. First births exhibit pronounced and steady seasonality, while second and subsequent births follow a vague seasonal pattern, suggesting that later births are more likely affected by self-choice and self-intervention. The analysis also reveals that the monthly distribution pattern of second births experienced a dramatic change following the roll-out of the selective-two-child policy and the Universal Two-child Policy in 2014 and 2016, changes that reflects the adjustments people made to achieve their fertility plans under the new policy.