Change in fertility rate and its influencing factors in 28 countries before and after the COVID-19 pandemic: linear modeling and interrupted time-series analysis

Objective To analyze the changes in fertility trends of seasonally and calendar adjusted fertility rate (SAFR) in different countries before and after the COVID-19 pandemic outbreak and investigate the influence factors. Methods Monthly SAFR data of 28 countries during January 2012 and December 2022 were collected in the Human Fertility Database (HFD). The node of December 2020 (9-month delay in gestation from the start of the March 2020 outbreak) was used as the point of division for comparison between the pre- (2012.1-2020.11) and post-pandemic (2020.12-2022.12) periods. Interrupted time series was used to analyze whether fertility rate trends (short-term fluctuations and long-term trends) changed before and after the pandemic in each country. Wilcoxon test was employed to analyze whether pre-pandemic fertility rate, GDP per capita, public health and social measures (PHSM) and unemployment rate were associated with the changes in fertility trends. Results Nineteen out of the 28 countries experienced a short-term decline in fertility rate after the pandemic, which subsequently rebounded. With respect to long-term trends, 2 countries shifted from a declining trend to an increasing trend, 8 countries shifted from an increasing trend to a declining trend, and 6 countries had their SAFR unchanged. The SAFR decline was mainly observed in some of the countries of Central Europe and the Western Mediterranean, while its increase was mainly in Northern and Western Europe. Pre-pandemic SAFR was lower in the countries with no short-term fluctuations in SAFR than those with short-term fluctuations (P=0.041). The countries with declining rate of SAFR had significantly lower pre-pandemic SAFR (P=0.005) and GDP per capita (P=0.027) than the countries with increasing rate of SAFR. No association was found between short-term fluctuations or long-term trends in fertility rate and the PHSM severity index or unemployment rate. Conclusion The COVID-19 pandemic has had varying short- and long-term impacts on SAFR in 28 countries, with the countries with relatively low economic levels and pre-pandemic SAFRs more vulnerable to further blows. The longer-term impacts of the COVID-19 pandemic on the populations of each country deserve further attention. X