STUDY QUESTION Did the first wave of the COVID-19 pandemic have an impact on monthly birth rates in Europe? SUMMARY ANSWER Using datasets on live births per month in Europe, collected from the Human Fertility Database, we found a −14.1% decline in live births in January 2021 (i.e. 9–10 months after the epidemic peaks and first lockdowns), compared to the average number of live births in January 2018 and 2019. WHAT IS KNOWN ALREADY Previous pandemics in the 20th and 21st centuries have been associated with a decline in birth rates 9 months after their peak, and a rebound in births over time. Lockdowns were necessary to control the first wave of the COVID-19 pandemic and may have had an impact on subsequent birth rates. STUDY DESIGN, SIZE, DURATION Monthly time series data on live births from January 2018 to March 2021 were extracted to provide a time-series analysis of birthrates during and after the first wave of the COVID-19 pandemic in 24 European countries. PARTICIPANTS/MATERIALS, SETTING, METHODS We conducted a random-effect generalized least squares regression to assess the seasonality of births from January 2018 to March 2021, and to identify potential differences in monthly live births after the first wave of the COVID-19 pandemic, considering the seasonality of births. To quantify these potential differences, we estimated the variation rate between the monthly live births observed during 2020 and 2021 and the mean of the 2018–2019 monthly live births in Europe. Factors potentially associated with a variation in monthly birth rates were assessed using univariable and multivariable generalized linear regressions. MAIN RESULTS AND THE ROLE OF CHANCE When considering the seasonality of births, January 2021 was the only month with a significant difference in live births. A drop of −14.1% was observed compared to the average number of live births in January 2018 and 2019. At the national level, this drop was observed 9–10 months after the epidemic peaks in 13 countries. The duration of lockdowns was the variable that had the stronger association with this decrease, whereas higher incomes per capita could be a factor limiting this decline. A rebound in births compared to the previous years occurred in March 2021 in 13 countries. LIMITATIONS, REASONS FOR CAUTION Our data are based on national data, limiting the power in the multivariable models used and the identification of other potential factors contributing to a decrease or an increase in birth rates. In addition, we collected only live births up to April 2021, which precludes the identification of a difference in births seasonality in 2021. WIDER IMPLICATIONS OF THE FINDINGS As with previous pandemics, the COVID-19 outbreak was associated with a decline in births 9 months after its first wave. This trend may be associated with the duration of the lockdowns. Although there was a rebound in births in the following months, it does not seem to compensate for this decline. STUDY FUNDING/COMPETING INTEREST(S) The authors receive no external funding and have no conflict of interest to declare. TRIAL REGISTRATION NUMBER N/A.