The compatibility of the simultaneous population growth and economic development has been preoccupying economists for centuries. However, today the problem of rapidly growing population is being replaced by the challenges of a reducing population, especially in countries with high levels of per capita income and welfare services - in short, in the welfare states. In order to achieve long-term reproduction, the total fertility rate (TFR) of a country must be around 2.1. Achieving this value is a major challenge for most of the developed states. Based on all of this, the paper models and examines the total fertility rate using linear regression and other data mining methods. This will be achieved with the help of WEKA open source program and data of twenty-two OECD countries. The primary goal is to identify the factors influencing TFR, and then to study how realistic it is for welfare states to achieve a total fertility rate of 2.1. The results closest to the reproduction level are obtained by linear regression and random forest, which are 1.761 and 1.893 respectively. Based on the results, the paper concludes that the short-term goal for welfare countries is to approach the desired value as closely as possible.