Prevalence and risk of Down syndrome in monozygotic and dizygotic multiple pregnancies in Europe: implications for prenatal screening. (4th February 2014)

• Record Type: Journal Article
• Authors: Boyle, B; Morris, JK; McConkey, R; Garne, E; Loane, M; Addor, MC; Gatt, M; Haeusler, M; Latos‐Bielenska, A; Lelong, N; McDonnell, R; Mullaney, C; O'Mahony, M; Dolk, H
• Is Part Of: BJOG. Volume 121:Number 7(2014:Jul.)
• Page Start: 809
• Page End: 820
• Publication Date: 2014-02-04
• Subjects: Obstetrics -- Periodicals; Gynecology -- Periodicals; 618
• DOI: 10.1111/1471-0528.12574
• Languages: English
• ISSNs: 1470-0328

Abstract

<abstract abstract-type="main" id="bjo12574-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="bjo12574-sec-0001" sec-type="section"> <title>Objective</title> <p>To determine risk of Down syndrome (DS) in multiple relative to singleton pregnancies, and compare prenatal diagnosis rates and pregnancy outcome.</p> </sec> <sec id="bjo12574-sec-0002" sec-type="section"> <title>Design</title> <p>Population‐based prevalence study based on EUROCAT congenital anomaly registries.</p> </sec> <sec id="bjo12574-sec-0003" sec-type="section"> <title>Setting</title> <p>Eight European countries.</p> </sec> <sec id="bjo12574-sec-0004" sec-type="section"> <title>Population</title> <p>14.8 million births 1990–2009; 2.89% multiple births.</p> </sec> <sec id="bjo12574-sec-0005" sec-type="section"> <title>Methods</title> <p>DS cases included livebirths, fetal deaths from 20 weeks, and terminations of pregnancy for fetal anomaly (TOPFA). Zygosity is inferred from like/unlike sex for birth denominators, and from concordance for DS cases.</p> </sec> <sec id="bjo12574-sec-0006" sec-type="section"> <title>Main outcome measures</title> <p>Relative risk (RR) of DS per fetus/baby from multiple versus singleton pregnancies and per pregnancy in monozygotic/dizygotic versus singleton pregnancies. Proportion of prenatally diagnosed and pregnancy outcome.</p> </sec> <sec id="bjo12574-sec-0007" sec-type="section"> <title>Statistical analysis</title> <p>Poisson and logistic regression stratified for maternal age, country and time.</p> </sec> <sec id="bjo12574-sec-0008" sec-type="section"> <title>Results</title> <p>Overall, the adjusted (adj) RR of DS for fetus/babies from multiple versus singleton pregnancies was 0.58 (95% CI 0.53–0.62), similar for all maternal ages except for mothers over 44, for whom it was considerably lower. In 8.7% of twin pairs affected by DS, both co‐twins were diagnosed with the condition. The adjRR of DS for monozygotic versus singleton pregnancies was 0.34 (95% CI 0.25–0.44) and for dizygotic versus singleton pregnancies 1.34 (95% CI 1.23–1.46). DS fetuses from multiple births were less likely to be prenatally diagnosed than singletons (adjOR 0.62 [95% CI 0.50–0.78]) and following diagnosis less likely to be TOPFA (adjOR 0.40 [95% CI 0.27–0.59]).</p> </sec> <sec id="bjo12574-sec-0009" sec-type="section"> <title>Conclusions</title> <p>The risk of DS per fetus/baby is lower in multiple than singleton pregnancies. These estimates can be used for genetic counselling and prenatal screening.</p> </sec> </abstract>