Individuals more strongly affiliated to religion have on average more children than less religious ones. Here, based on census data of 3 658 650 women aged 46–60 years from 32 countries provided by IPUMS International and data from the Wisconsin Longitudinal Study (n= 2400 women, aged 53–57 years), we show that religious homogamy is also associated with higher reproduction in terms of a higher number of children and a lower chance of remaining childless. We argue that, together with the relationship between general religious intensity and number of children, religious homogamy has reproductive consequences. These may impact future demographic developments and could have also played a role in the biological evolution of humans.