The Impact of Down Syndrome Screening on Taiwanese Down Syndrome Births: A Nationwide Retrospective Study and a Screening Result from a Single Medical Centre

Abstract

A retrospective analysis of the Taiwanese National Birth Defect Registration and Notification System was conducted in order to determine the live birth- and stillbirth rates in infants with Down syndrome, trisomy 18, trisomy 13 and Turner syndrome between 2001 and 2010. The objective was to investigate the impact of Down syndrome screening on the Taiwanese Down syndrome live birth rate. In addition, the results of first-trimester Down syndrome screening between 2006 and 2011, and of second-trimester quadruple testing between 2008 and 2011, were obtained from the National Taiwan University Hospital. All Taiwanese infants born between 2001 and 2010 were included in the first part of the analysis, and women receiving first-trimester Down syndrome screening or second-trimester quadruple testing from the National Taiwan University Hospital were included in the second part. The live birth rate of infants with Down syndrome, per 100 000 live births, decreased from 22.28 in 2001 to 7.79 in 2010. The ratio of liveborn DS to total DS was 48.74% in 2001, and then decreased to 25.88% in 2006, when first-trimester screening was widely introduced in Taiwan. This ratio dropped to 20.64% in 2008, when the second-trimester quadruple test was implemented. The overall positive rate in first-trimester screening in the National Taiwan University Hospital was 3.1%, with a Down syndrome detection rate of 100%; the quadruple test had values of 9.0% and 75%, respectively. The use of first-trimester screening and the second-trimester quadruple test may be responsible for the marked decrease in the Taiwanese Down syndrome live birth rate observed between 2001 and 2010.

Has Noninvasive Prenatal Testing Impacted Termination of Pregnancy and Live Birth Rates of Infants With Down Syndrome?

“…44 In Taiwan, a termination rate of 67.5% was reported for 2001 45 ; however, prenatal screening and diagnosis has since been more widely introduced and the live birth rate for children with DS decreased from 48.7% in 2001 to 6% in 2010. 23 Comparison between termination rates reported prior to the introduction of NIPT with termination rates seen in the reviewed studies and audits suggests a general trend towards a decrease in termination rates compared with pre-NIPT rates (Table 2). Data from the UK audit and research studies [35][36][37] indicate that termination rates for women having NIPT are considerably lower than the pre-NIPT termination rate of 92%.…”

“…11,18 It is not yet clear, however, whether the increase in the numbers of women having prenatal testing will directly result in more terminations of pregnancy. There will be wide variation in the number of children born with DS between and even within countries depending on atti- These figures vary between countries: in the United States there were 30% fewer individuals with DS (2007), 19 50% fewer in the Netherlands (2015), 20 48% fewer in England and Wales (2008), 21 55% fewer in Australia (2004), 22 94% fewer in Taiwan (2010), 23 and 55% fewer in China (2011). 24 As the numbers of older women giving birth have grown, the numbers of pregnancies affected with DS have also increased.…”

Has noninvasive prenatal testing impacted termination of pregnancy and live birth rates of infants with Down syndrome?

“…Several studies conducted prior to the introduction of NIPT have reported the number of children born with DS compared to expected numbers based on the prevalence of DS in the general population. These figures vary between countries: in the United States there were 30% fewer individuals with DS (2007), 50% fewer in the Netherlands (2015), 48% fewer in England and Wales (2008), 55% fewer in Australia (2004), 94% fewer in Taiwan (2010), and 55% fewer in China (2011) . As the numbers of older women giving birth have grown, the numbers of pregnancies affected with DS have also increased.…”

Integrated care for Down syndrome

“…In 2005 and 2008, this program was modified to perform screening during the first or second trimester and to use a combined test for nuchal translucency thickness, hCG and pregnancy‐associated plasma protein‐A (PAPP‐A) or the quadruple test (hCG, AFP, uE3, and inhibin A) (Chou et al, , Shaw et al, , Shaw et al, ). The first and second trimester DS screening percentage is approximately 48.7% in Taiwan (Lin et al, ). According to the literature, the detection rate for the second trimester double test is 56‐61%, the first trimester combined test is 82.0–87.5%, and the second trimester quadruple test is 81% in Taiwan (Shaw et al, , Shaw et al, ).…”