According to the 7th National Population Census of China, the estimated rate of childlessness for women aged 49 is 5.16% in 2020, lower than that reported in the European Union (19%) and in the United States (11%). The heterogeneity of childlessness in China is increasing, showing distinct differences regarding to period, cohort, education, place of residence, and regions. The childlessness level of women aged 49 with high levels of education, living in cities and regions with ultra-low fertility levels is much higher. Factors like the acceleration of urbanization, the continued popularization of higher education, and the ongoing trend of marriage and childbearing delay would further promote the rise of the childlessness level. Given China's low share of non-marital births and third births and above, the continuous rise of childlessness level would have a stronger negative impact on the newborn population and total fertility rates, thereby affecting China's ability to maintain the aimed suitable fertility level. The government should attach great importance to and address the issue in advance.

Based on the analysis of national birth monitoring data, this paper suggests that declining number of births in recent years in China is driven jointly by the reduction of births among women aged below 30, the decrease of first births and the waning growth of the second births. The outbreak of COVID-19 further drastically depressed the number of births among women aged below 30 and reduced the number of first births in the fourth quarter of 2020, resulting in an accelerated decline in the number of births in 2020.

 This study examines the trends in and the impact of birth spacing policy on the second birth interval in China since 1970s using the population monitoring data in 121 Chinese counties．The birth spacing policy plays a significant role in regulating people’ s fertility behaviors thus slowing down population growth in China．Specifically，changes in second birth intervals have gone through three stages，a long-term stability before 1990s，an increase from 1990 to 2005 and a decline since 2006， implying a dynamic relationship with the birth interval regulation．Conditions for continuing the current birth spacing policy aiming at later birth，longer interval and less children no longer exist．Thus，the focus on birth spacing needs to be switched from a policy orientation to a health orientation．

This study examines the trends in and the impact of birth spacing policy on the second birth interval in China since 1970s using the population monitoring data in 121 Chinese counties．The birth spacing policy plays a significant role in regulating people’ s fertility behaviors thus slowing down population growth in China．Specifically，changes in second birth intervals have gone through three stages，a long-term stability before 1990s，an increase from 1990 to 2005 and a decline since 2006，implying a dynamic relationship with the birth interval regulation．Conditions for continuing the current birth spacing policy aiming at later birth，longer interval and less children no longer exist．Thus，the focus on birth spacing needs to be switched from a policy orientation to a health orientation．