title: The impact of national prenatal screening on the time of diagnosis and outcome of pregnancies affected with common trisomies, a cohort study in the Northern Netherlands.
abstract: To evaluate the impact of the introduction of prenatal screening on time of detection and pregnancy outcome for trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13).
  
  
  
  We performed a retrospective, population-based cohort study in the Northern Netherlands including 503 trisomy cases born between 2005 and 2012. Screening tests and invasive procedures, timing of diagnosis and pregnancy outcome were compared between the period before (2005-2006) and after introduction (2007-2012) using X2tests.
  
  
  
  There was an increase in proportion of women who had a prenatal screening and/or invasive test, from 62% in 2005-2006 to 84% in 2010-2012 (p < 0.01), while the proportion of prenatally diagnosed cases did not change (60% overall). In women < =35 years 47% of the cases were diagnosed prenatally vs 73% in women >35 years (p < 0.01). More T13/T18 cases were diagnosed <24 weeks after introduction (62% vs 84%; p < 0.01). In T13/T18 intra-uterine death decreased (26% vs 15%), while terminations increased: 55% vs 72%.
  
  
  
  The introduction of prenatal screening had limited impact on the time of detection and outcome of the most common trisomies. The introduction of the 20-week anomaly scan has resulted in more trisomy cases diagnosed <24 weeks and a shift from fetal death to terminations.
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Genetics, PO Box 30001, 9700 RB, Groningen, The Netherlands.
authors.forename: Katelijne
authors.initials: K
authors.lastname: Bouman
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Genetics, PO Box 30001, 9700 RB, Groningen, The Netherlands. m.k.bakker@umcg.nl.|University of Groningen, University Medical Center Groningen, Department of Obstetrics, PO Box 30001, 9700 RB, Groningen, The Netherlands. m.k.bakker@umcg.nl.
authors.forename: Marian K
authors.initials: MK
authors.lastname: Bakker
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Genetics, PO Box 30001, 9700 RB, Groningen, The Netherlands.
authors.forename: Erwin
authors.initials: E
authors.lastname: Birnie
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Genetics, PO Box 30001, 9700 RB, Groningen, The Netherlands.
authors.forename: Lies
authors.initials: L
authors.lastname: Ter Beek
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Obstetrics, PO Box 30001, 9700 RB, Groningen, The Netherlands.
authors.forename: Caterina M
authors.initials: CM
authors.lastname: Bilardo
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Genetics, PO Box 30001, 9700 RB, Groningen, The Netherlands.
authors.forename: Irene M
authors.initials: IM
authors.lastname: van Langen
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Genetics, PO Box 30001, 9700 RB, Groningen, The Netherlands.
authors.forename: Hermien E K
authors.initials: HE
authors.lastname: de Walle
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D025063:Chromosome Disorders / Q000175:diagnosis*; D004314:Down Syndrome / Q000175:diagnosis; D005260:Female; D006291:Health Policy; D006801:Humans; D008403:Mass Screening / Q000331:legislation & jurisprudence*; D009426:Netherlands; D011247:Pregnancy; D011256:Pregnancy Outcome; D011296:Prenatal Diagnosis / Q000379:methods / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D013997:Time Factors; D000073839:Trisomy 13 Syndrome / Q000175:diagnosis; D000073842:Trisomy 18 Syndrome / Q000175:diagnosis
keywords: Maternal age; Pregnancy outcome; Prenatal screening; Trisomy 13; Trisomy 18; Trisomy 21