Authors:
Maxwell S, Bower C, O'Leary P.
Authors notes:
Prenat Diagn. 2015;35(13):1324-30.
Keywords:
Down syndrome, Western Australia, prenatal diagnosis, fetal termination, aneuploidy 39
Abstract:
Objective: To assess how prenatal screening and diagnostic testing have impacted the diagnosis, termination and birth prevalence of Down syndrome in Western Australia (1980-2013).
Method: We analysed trends in termination rates and birth prevalence of Down syndrome using aggregated data (1980-2013).
We modelled the expected live-birth rate and prevalence of Down syndrome and compared different eras of screening and diagnosis with respect to the impact on live-birth rate and prevalence of Down syndrome.
Results: Between 1980 and 2013, the rate of Down syndrome pregnancies increased, corresponding to a greater proportion of babies born to older women.
Following the introduction of screening in 1994, the rate of live-born infants with Down syndrome reduced significantly (p=0.001).
The rate of terminations of pregnancy for Down syndrome remained stable over this period.
In the absence of termination, the Down syndrome live-birth rate would have risen from 1.1 per 1000 to 2.17 per 1000 between 1980 and 2013.
Conclusion: Prenatal testing in Western Australia has reduced the birth prevalence of Down syndrome despite an increased rate of Down syndrome pregnancies.
Most women for whom a prenatal diagnosis of fetal Down syndrome is made, chose to terminate the pregnancy (93%), and this proportion has not changed over the study period.