title: Risk of fetal loss associated with invasive testing following combined first-trimester screening for Down syndrome: a national cohort of 147,987 singleton pregnancies.
abstract: OBJECTIVE
  To assess prospectively the risk of fetal loss associated with chorionic villus sampling (CVS) and amniocentesis (AC) following combined first-trimester screening (cFTS) for Down syndrome.
  
  
  METHODS
  This was a nationwide population-based study (Danish Fetal Medicine Database, 2008-2010) including 147,987 women with singleton pregnancy who underwent cFTS. Propensity score stratification was used to assess the risk of fetal loss with and without invasive testing. Analyses were performed between 3 and 21 days after cFTS for CVS and between 28 and 42 days after cFTS for AC. Results are reported as average risk differences with 95% CIs.
  
  
  RESULTS
  The risks of miscarriage and stillbirth were not higher in women exposed to CVS or AC compared with unexposed women, independent of the analysis time-point. The average effect of CVS on risk of miscarriage was -0.08% (95% CI, -0.64; 0.47) at 3 days and -0.21% (95% CI, -0.58; 0.15) at 21 days after cFTS, while the effect on risk of stillbirth was -0.18% (95% CI, -0.50; 0.13) at 3 days and -0.27% (95% CI, -0.58; 0.04) at 21 days after cFTS. Regarding the effect of AC on risk of miscarriage, the analysis at 28 days after cFTS showed an average effect of 0.56% (95% CI, -0.21; 1.33), while the effect on risk of stillbirth was 0.09% (95% CI, -0.39; 0.58) at 42 days after cFTS.
  
  
  CONCLUSIONS
  Neither CVS nor AC was associated with increased risk of miscarriage or stillbirth. These findings indicate that the procedure-related risk of CVS and AC is very low.
authors.affiliation: Center of Fetal Medicine, Department of Obstetrics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.|Faculty of Medicine and Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: C B
authors.initials: CB
authors.lastname: Wulff
authors.affiliation: Section of Biostatistics, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: T A
authors.initials: TA
authors.lastname: Gerds
authors.affiliation: Center of Fetal Medicine, Department of Obstetrics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.|Department of Clinical Biochemistry, Copenhagen University Hospital, Herlev and Gentofte Hospital, Copenhagen, Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Rode
authors.affiliation: Center of Fetal Medicine, Department of Obstetrics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors.forename: C K
authors.initials: CK
authors.lastname: Ekelund
authors.affiliation: Fetal Medicine Unit, Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby, Denmark.
authors.forename: O B
authors.initials: OB
authors.lastname: Petersen
authors.affiliation: Center of Fetal Medicine, Department of Obstetrics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.|Faculty of Medicine and Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Tabor
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology*; D000328:Adult; D000649:Amniocentesis / Q000706:statistics & numerical data*; D016022:Case-Control Studies; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000378:metabolism; D015193:Chorionic Villi Sampling / Q000706:statistics & numerical data*; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism; D057216:Propensity Score; D012189:Retrospective Studies; D012306:Risk; D050497:Stillbirth / Q000453:epidemiology*; D016216:Ultrasonography, Prenatal; D055815:Young Adult
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A; C579283:PAPPA protein, human
keywords: amniocentesis; chorionic villus sampling; combined first-trimester screening; fetal loss; invasive prenatal testing; miscarriage; procedure-related risk; stillbirth