Long-term trends for socio-economic differences in prenatal diagnosis of Down syndrome: diffusion of services or persistence of disparities?

OBJECTIVE: To assess long-term trends in disparities for prenatal diagnosis of Down syndrome in relation to policy changes.

DESIGN: Population-based observational study.

SETTING: Paris.

POPULATION: Residents of Paris who gave birth or had a termination of pregnancy in Paris during 1983-2003 (approximately 23,000 births per year).

METHODS: Using population-based data from the Paris Registry of Congenital Malformations on 1934 cases of Down syndrome, we assessed differences in prenatal diagnosis proportions by maternal profession and geographical origin for the years 1983-2003. Analyses included locally weighted scatter plot smoother curves and binomial regression.

MAIN OUTCOME MEASURE: Trends in proportion of Down syndrome cases diagnosed prior to birth for different maternal occupation groups and women of different geographical origins.

RESULTS: The proportion of prenatally diagnosed cases increased substantially, reaching to about 85-90% of cases in 2003 for most socio-economic groups. This increase was accompanied by a significant decrease in disparities in prenatal diagnosis. Nonetheless, the proportion of prenatally diagnosed cases remained 12% lower for women without a profession compared with those in the highest occupational category (maternal age-adjusted risk difference -12.0%, 95% CI -17.1 to -6.9).

CONCLUSIONS: Together with the implementation of policies aimed at providing access to prenatal screening for all women, socio-economic differences in prenatal diagnosis of Down syndrome decreased over time. These trends need to be monitored, particularly in light of technical advances and alternative strategies for prenatal testing. However, while monitoring the proportion of cases with prenatal diagnosis is important, the ideal evaluation of prenatal testing programmes should also include measures of informed choice.