Does being born to non-married parents affect a child's prospects? It is a question that is notoriously hard to answer. BBC Education Editor Branwen Jeffreys investigates research from Princeton's landmark Fragile Families study, which has gathered data from 5,000 births over the last 18 years. She speaks to principal investigator Professor Sara McLanahan to find out how much we know about the differing outcomes of children raised by married, cohabiting or single parents.

Branwen asks how applicable the results of the study are to British society, where very soon, a minority of births will be to married parents. Professor Emla Fitzsimons has been following the lives of 19,000 children, born across the UK in 2000-01. She reveals what the project, know as The Millennium Cohort Study has found.