Identifying emerging reproductive vulnerability: an approach to decompose differences in total fertility.

PURPOSE: We introduce a method to partition the difference in total fertility between two groups. METHODS: We computed the total fertility rate for Francophones and Anglophones of Quebec, Canada, between 1989-1993 and 2004-2008. We partitioned the difference in excess fertility for one group relative to the other into the number of children contributed by maternal age, origin, material deprivation, education, and offspring birth order. We calculated the change in total fertility over time and the factors that contributed. RESULTS: The total fertility rate was higher by 0.18 children for Francophones in 1989-1993, but the gap reversed in 2004-2008, with total fertility higher for Anglophones by 0.12 children. Francophones had higher fertility in 1989-1993 due mainly to women who were Canadian born, aged 15-29 years, without secondary diploma, or living in socioeconomic deprivation. The reversal in 2004-2008 was caused by a reduction in fertility for Francophones aged 15-29 years and an increase in the contribution of Anglophones who were foreign born, aged 30-49 years or socioeconomically disadvantaged. CONCLUSIONS: Through decomposition of differences in total fertility, we identified populations with emerging reproductive vulnerability in a large Canadian province. Socioeconomically disadvantaged Anglophones in Quebec have increasing fertility, a potential sign of increasing reproductive risk.