EN
Regular changes in economic phenomena that are observed in the long term are also to be found in demographic phenomena. This paper focuses on identifying and measuring cyclical fluctuations of variables characterising the process of births. Two variables have been chosen for the study: the number of births and the female fertility rate. The long time series of variables in France and Sweden have been chosen for the applied procedure. The regularly repeating changes to demographic variables are referred to as baby booms and demographic lows. However, no consideration is given to the duration of the cycle or the intensity of its individual phases. That is why the study attempted to identify and measure the cyclical fluctuations in demographic variables, making use of the achievements of business cycle researchers, while adapting them for its own research purposes.