The article presents a method for constructing an age-related fertility model based on the modern system of statistical accounting in Russia. In analyzing the birth rate, it is advisable to use indicators for both calendar years and real generations. The first ones include age-related fertility rates and the structure of their contributions to the total fertility, the average age of the mother at the birth of children. The use of annual age-related fertility rates allows us to make an estimated calculation of fertility rates for real generations, including those characterizing the age model, which significantly depends on the structure of fertility: the more children are born second, third, and subsequent in the order of birth, the more the age model of fertility will be shifted to older ages.It is established that to characterize the age model of fertility, fertility indicators (both for conditional and real generations) should be used, taking into account the order of birth. It is noted that changes in the level and age model of fertility for calendar years may be due to the influence of timing shifts associated with the birth of children at a younger age or, conversely, the postponement of births in many families.The study of indicators for calendar years allowed us to hypothesize the presence of such timing shifts, and the results of the analysis of fertility rates in age ranges for real generations confirmed the hypotheses. All the indicators used in the article are calculated using the data of the All-Russian Population Census of the 2020 round.