There is mounting evidence of a complex system of multi-directional links between fertility, productivity and inequality. The contribution of this study is a multi-country analysis of these three variables as a simultaneous system in a VECM framework using annual time series data for the UK, USA, Australia, Japan, and Sweden. The results highlight some differences between countries in the relationships between the variables. For the UK and Australia, the VECM analysis reveals a long run relationship between fertility and productivity to which both fertility and productivity adjust. This calls into question pro-fertility policies in these countries that aim to offset the costs of population ageing, because an increase in fertility may be associated with lower productivity in the long run. The results for the USA suggest that raising productivity in the long run will be associated with a decrease in both inequality and fertility. No significant long run relationships were found for Japan and Sweden.