Why are there more unplanned births in the UK than in France? A comparative analysis between the French ELFE and the UK Millennium birth cohorts

International audienceCONTEXT. Whether the pregnancy was planned is one of the factors that could have long-term consequences for the child. Despite widespread use of contraception and abortion, the proportion of births following an unplanned pregnancy remains high but variable between developed countries.OBJECTIVE. To compare the proportion of unplanned births in the UK and in France and to explore if the socioeconomic or demographic characteristics of the parents could explain the much higher level of unplanned pregnancies in the UK.DATA. Two large birth cohorts with nationally representative samples: the French ELFE cohort having recruited 18,322 families with children born in 2011 and the UK Millennium Cohort Study (MCS) covering 18,552 families with children born in 2000-2002.RESULTS AND DISCUSSION. The MCS has already exhibited a high level of unplanned births (41%). ELFE data will be available imminently and the rate of unplanned births is expected to be below 20%. In the UK, unplanned births occurred mainly among low educated mothers, large families, young mothers and mothers without partners. We will test if the differences in unplanned pregnancies between France and the UK could be explained by differentials in such characteristics of the families recruited into the two cohorts