Stepfamilies in Denmark and France: does the number of previous children from both partners and whether the previous children reside with the couple influence fertility?

In both Denmark and France, the past decades have shown profound changes in the patterns of fertility as well as in family formation and family dissolution, with no related decline in overall fertility. Using very large data sets (380,000 respondents in the French survey, 1.3 million women in Danish Register data), we built synthetic indexes to show the frequency of stepfamilies in both countries. It is more frequent in Denmark than in France. We then analyse fertility of stepfamilies, compared to couples without any child born before the union, with controlling for age, duration of union, age of last child, and level of education. Our variables of interest are the number of stepchildren, whether they come from the man or the woman, whether they live with the couple or not. Preliminary analysis show several interactions and non monotonous variations, as well as strong interactions with the number of shared children.