The nature of infradian rhythmicity remains to be fully elucidated. On the one said, there is evidence of the endogenous nature of infradian biological rhythms, on the other said, there is evidence of exogenous influences on infradian rhythmicity. The purpose of this research: to test the hypothesis about the rhythmic nature of the frequency of childbirth and its coordination with the cyclical weather conditions in the city of Barnaul. Materials and methods. We analyzed changes in weather conditions and data on the frequency of births over a period of 1998 and 2014 years, which were selected for the collection and analysis of materials, as the years with the most typical climatic indicators for the region (temperature, atmospheric pressure and baric gradient), as well as because of the comparable level of solar activity in these years, which fell in the middle of the ascending branch of the Schwabe cycle. However, the samples were not identical, which increased the possibility of determining the probabilistic course of events. To determine the spectral characteristics in the dynamics of time series and their frequency matching, we used the methods of Fourier analysis for individual time series and cross-spectral analysis when comparing two time series. Results. Based on the results of two repetitions, it was found that in the dynamics of the birth frequency there are periodic components in the infradian range with periods 33,00, 18,00, 12,00, 7.00, 6.75, 2.42 day. The rhythms of the birth frequency are synchronized with the wave dynamics of air temperature at frequencies with periods of 14, 7 and 3 days, with the dynamics of air pressure – at frequencies with periods of 7, 5 and 3 days, and with the dynamics of the pressure gradient at frequencies with periods of 11, 5 and 2 days. Conclusions. The agreement between the rhythms of the birth frequency and the rhythms of the meteorological parameters indicates the influence of the exogenous factor on the infra-rhythmogenesis of the birth frequency. The paper discusses possible mechanisms of infra-rhythmogenesis of birth frequency, meteorological indicators, and their mutual agreement.