This paper seeks to find a sustainable model for projecting the distribution of Portuguese age-specific fertility rates using data drawn from 1960 to 2000. For this purpose, an econometric model was developed using annual data to explain the changes in fertility rates based on their historical development

Explanatory exogenous variables were not used since, in order to make projections within a time frame of this magnitude, it would be necessary to project the variables themselves. The chosen model uses a curve that has been adjusted to the distributions of age-specific Portuguese fertility in the years of the data and ARIMA models to project the parameters of the curve for the future. We concluded that Portuguese fertility will undergo a slightly upward trend until the year 2050 with small changes occurring in the distribution of agespecific fertility, reflecting an increase in the relative fertility rates after the age of 29 and their decrease in younger ages.

key words: fertylity, econometric models, ARIMA models, projections