A third child - a new trend?

Lotta Persson, Statistics Sweden

The study focuses on third-birth fertility. The reason for this is the increase since the late 1990s. In a cox proportional hazard regression the relative risk for having a third child for two-child mothers is explored. When controlling for socio-economic and demographic changes since the late 1990s, it turns out that the upward trend only partly has socio-economic and demographic explanations. A reasonable explanation is that having a third child is a new trend and it seems that this new trend is stronger in metropolitan areas and in the suburbs. Thus it seems likely that additional explanations to the third-birth fertility increase exist, beyond structural changes. Such an explanation could be the presence of social interaction effects. In this study, neighbourhood effects are in focus. Is it more common for mothers of two children to have a third child if they live in a neighbourhood where others have had many children? In this register study we have information on child-densities in 7 200 neighborhoods 1997–2008. It turns out that the propensity to have a third child is greater among those who the previous year lived in an area with high child density. This applies especially to two-child mothers who lived in detached houses in metropolitan areas and in the suburbs. The results apply even after controlling for differences regarding age, birth country group, educational level, employment status, disposable income level, type of family and dwelling size.