The influence of income on family fertility in the light of the results of empirical studies

Based on data from the 1973-83 Polish Family Budget Survey, this study examines the influence of income as a source of maintenance and income as a determinant of childbearing on family parity. It is assumed that income influences parity as a source of maintenance and as an influence on lifestyle or reproductive behavior. As a source of maintenance, the influence will be positive. As a life-style factor, it could be positive or negative. The hypotheses are 1) that positive influences are characteristics of older couples with a lower educational level and living in villages and small towns and income is a source of maintenance, and 2) a negative influence on parity reflects younger couples with higher educational levels from larger cities and income is a life-style factor. Some examples of how the theory of income influences total fertility are given in addition to a further elaboration of the theory. Other concepts introduced, as related to childbearing, are the value of goods and services with unchanged preferences and an increase in income, with preferences changing with income increases, with income preferences for nonprocreational and for procreational needs, and income as a factor influencing procreational needs and behavior. Correlation analysis is conducted for 33 subpopulations based on duration of marriage, educational level of the household, and size of residence. The results indicate that, in years 1973, 1975, and 1978 when income and parity are significant, the sign is positive. In 1980, there was a decrease in the number of subpopulations with a significant relationship, and in 3 subpopulations the results were negative. The 13 positive subpopulations were similar to those in the 1970s. In 1983, income explained an even smaller amount of parity. The subpopulations with a postive relationship usually have longer marriage durations, which suggest income as a source of maintenance. Negative results were among subpopulations with shorter marriage durations, which suggests life-style factor effects of income.