3. Summary of study characteristics.
| Study | NT, PAPP‐A, free ßhCG and age | Nasal bone | NT and age | NT | Maternal age (range) in years | Reference standard | Population | Study design | Study location |
| Acacio 2001 | X | Mean 35.8 (21‐45) | CVS biopsy, amniocentesis or blood or placenta used for fetal karyotyping | High‐risk referral for invasive testing | Retrospective study of patient notes | South America | |||
| Audibert 2001 | X | Mean 30.1, all < 38, 86% < 35, 14% ≥ 35 | Prenatal karyotype conducted (in 7.6% of patients) depending on presence of risk > 125, high maternal age, parental anxiety, history of chromosomal defects or parental translocation or abnormal second trimester scan age | Routine screening | Prospective consecutive series | France | |||
| Babbur 2005 | X | Median 37 (19‐46) | Invasive testing offered to women with NT > 3 mm or risk > 1:250 as defined by combined NT and serum results (CVS from 11 weeks, amniocentesis from 15 weeks). Rapid in situ hybridisation test in patients with risk > 1:30. No details given of any follow‐up to birth | Women requesting screening (self‐paying service) and women attending on account of previous pregnancy history of fetal abnormality | Prospective cohort | UK | |||
| Barrett 2008 | X | Mean 34.9 for screen positives, 30.5 for screen negatives | Karyotyping or follow‐up to birth | Routine screening | Cohort | Australia | |||
| Belics 2011 | Mean 36.4 (15‐46) for Down's cases, 29.8 (15‐49) for unaffected pregnancies | Amniocentesis or CVS (85% of women) or follow‐up to birth | High‐risk referral for invasive testing | Cohort | Budapest | ||||
| Benattar 1999 | X | Mean 32 (16‐46), 8.3% > 35 | Amniocentesis due to maternal age > 38 years (6.1% or women). Karyotyping encouraged for women with positive result on one or more index test. No details of reference standard for index test negative women | Routine screening | Prospective cohort | France | |||
| Bestwick 2010 | X | X | X | Median 39 for Down's cases, 34 for unaffected pregnancies | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | UK | |
| Biagiotti 1998 | X | X | Unclear (maybe all ≥ 38) | Amniocentesis or CVS | High‐risk referral for invasive testing | Case control | Italy | ||
| Borenstein 2008 | Median 35 (17‐49) | CVS | High‐risk referral for invasive testing | Prospective cohort | UK | ||||
| Borrell 2005 | X | X | Not reported | CVS (high‐risk women) or follow‐up to birth | Routine screening | Retrospective cohort | Spain | ||
| Borrell 2009 | X | Mean 32 | Karyotyping or follow‐up to birth | Routine screening and high‐risk referral | Prospective cohort | Spain | |||
| Brameld 2008 | X | Median 31 (14‐47), 20% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | Australia | |||
| Brizot 2001 | X | Median 28 (13‐46), 19.4% ≥ 35 | Antenatal karyotyping (5.9% of pregnancies: 62% of high‐risk, 29% of medium‐risk and 3% of the low‐risk women). Follow‐up to birth (85.3% of women) | Routine screening | Prospective cohort | Brazil | |||
| Centini 2005 | X | ≥ 35 (35‐44) | Amniocentesis in women high risk on screening (16.2%). Follow‐up at birth in women who were low risk on screening | High‐risk patients undergoing routine screening | Retrospective cohort | Italy | |||
| Chasen 2003 | X | Median 33 (IQR 31‐36), 36.2% ≥ 35 | Karyotyping or follow‐up to birth in 96.1% of patients | Routine screening | Prospective consecutive cohort | USA | |||
| Chen 2009 | Median 30 (20‐44) for Down's cases, 32 (19‐40) for controls | Karyotyping or follow‐up to birth | Routine screening | Case control | China | ||||
| Christiansen 2005 | X | Not reported | Karyotyping | Screening programmes for syphilis and Down's syndrome | Case control | Denmark | |||
| Christiansen 2009 | X | Median 37.5 for Down's cases, 36.4 for controls | Karyotyping or follow‐up to birth | Routine screening | Case control | Denmark | |||
| Christiansen 2010 | X | Median 36 (25‐44) for Down's cases, 29 (17‐45) for controls | Karyotyping or follow‐up to birth | Routine screening | Case control | Denmark | |||
| Cicero 2004a | Median 37 (16‐48) | CVS | High‐risk referral for invasive testing | Prospective cohort | USA | ||||
| Cicero 2006 | X | Median 35 (18‐50) | CVS or amniocentesis (in high risk women) or follow‐up to birth | Routine screening | Prospective cohort | UK | |||
| Cocciolone 2008 (first trimester screening cohort) | X | Median 31.3 | Karyotyping or follow‐up to birth | Routine screening | Cohort | Australia | |||
| Cowans 2009 | X | Mean 38 (16‐49) for Down's cases, 29 (13‐56) for unaffected pregnancies | Karyotyping or follow‐up to birth | Routine screening | Cohort | UK | |||
| Cowans 2010 | X | Mean 37.0 (IQR 32.9‐40.5) for Down's cases, 32.4 (IQR 29.0‐35.9) for controls | Karyotyping or follow‐up to birth | Routine screening | Case control | UK | |||
| Crossley 2002 | X | X | Median 29.9, 15.4% ≥ 35 | CVS (offered where women had high NT measurements), amniocentesis or follow‐up to birth | Routine screening | Prospective cohort | UK | ||
| De Graaf 1999 | X | X | Not reported | CVS and amniocentesis | High‐risk referral for invasive testing | Case control | Netherlands | ||
| Ekelund 2008 | X | Not reported | Karyotyping or follow‐up to birth | Routine screening | Cohort | Denmark | |||
| Gasiorek‐Wiens 2001 | X | Median 33 (15‐49), 36.1% > 35 | CVS, amniocentesis or follow‐up to birth | Routine screening | Prospective cohort | Germany, Switzerland and Austria | |||
| Gasiorek‐Wiens 2010 | X | Median 35.1 (13.2‐46.7) | Karyotyping or follow‐up to birth | Routine screening | Cohort | Germany | |||
| Go 2005 | X | 49% ≤ 35, 51% ≥ 36 | Invasive testing or follow‐up to birth | Routine screening | Retrospective cohort | Netherlands | |||
| Gyselaers 2005 | X | X | Not reported | CVS, amniocentesis or follow‐up to birth | Routine screening | Prospective cohort | Belgium | ||
| Habayeb 2010 | Median 35.4 (18‐49) | Karyotyping or follow‐up to birth | Routine screening | Cohort | UK | ||||
| Hadlow 2005* | X | Mean 30.7, 21.2% ≥ 35 | CVS, amniocentesis or follow‐up to birth | Routine screening | Prospective cohort | Australia | |||
| Hafner 1998* | X | Median 28 (15‐49) 6.9% ≥ 35 | Amniocentesis or CVS in patients with previous Down’s pregnancy, > 35 years or with a positive biochemical test result. Other women underwent scan at 22 weeks and, if NT >2.5 mm special examination directed to examination of fetal heart. Follow‐up to birth | Routine screening | Prospective cohort | Austria | |||
| Has 2008 | X | X | X | Median 28.3 (17‐45) | Karyotyping or follow‐up to birth | Routine screening | Cohort | Turkey | |
| Hewitt 1996 | X | Median 37 (21‐48) | CVS | High‐risk referral for invasive testing | Prospective cohort | Australia | |||
| Hormansdorfer 2011 | X | Mean 31.1 (16‐46), 22% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Germany | |||
| Huang 2010 | X | Median 30 (15‐47), mean 29.8 (SD 3.3) | Karyotyping or follow‐up to birth | Routine screening | Cohort | Taiwan | |||
| Jaques 2007 | X | Mean 33 (16‐51), 18.5% ≥ 37 | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | Australia | |||
| Jaques 2010 FTS (first trimester screening) | X | Mean 16.3% ≥ 37 | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | Australia | |||
| Kagan 2010 | X | X | Mean 35.4 (14.1‐52.2) | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | UK | ||
| Kim 2006 | X | Mean 29.9 (SD 3.3) | Amniocentesis or CVS in patients considered high risk (NT > 2.5, aged > 35 years, positive biochemical test result, history or chromosomal abnormality, fetal structural abnormality at ultrasound or other reason). Follow‐up to birth | Routine screening | Retrospective cohort | South Korea | |||
| Koster 2011 | X | Median 37 (IQR 36‐39) | Karyotyping or follow‐up to birth | Routine screening | Case control | Netherlands | |||
| Kozlowski 2007 GC (Gynaecologists' practices) | X | X | Median 32 (15‐48), 26.4% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Cohort | Germany | ||
| Kozlowski 2007 PC (Prenatal centre) | X | X | Median 34 (14‐46), 43.2% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Cohort | Germany | ||
| Krantz 2000* | X | X | 34.7% ≥ 35 | Not reported | Routine screening | Prospective cohort | USA | ||
| Kublickas 2009 | X | 51% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Sweden | |||
| Kuc 2010 | X | Not reported | Karyotyping or follow‐up to birth | Routine screening | Case control | Netherlands | |||
| Lam 2002 | X | Mean 30.5 (19% ≥ 35) for unaffected pregnancies | Women considered high risk offered CVS (0.7%) or amniocentesis (11.8%). Follow‐up to birth | Routine screening | Prospective cohort | Hong Kong | |||
| Leung 2009 | X | X | Median 32 (IQR 30‐35), 27.4% ≥ 35 | Amniocentesis or follow‐up to birth | Routine screening | Prospective cohort | China | ||
| MacRae 2008 | X | Not reported | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | UK | |||
| Maiz 2007 | Median 35 (17‐49) | CVS | High‐risk referral for invasive testing | Prospective cohort | UK | ||||
| Maiz 2009 | Median 34.5 (14.1‐50.1) | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | UK | ||||
| Malone 2004 | X | Mean 30.1 (16‐47), 22.1% ≥ 35 | Amniocentesis (in women considered high risk, n = 510) or follow‐up to birth | Routine screening | Prospective cohort | USA | |||
| Malone 2005 | X | 21.6% ≥ 35 | Amniocentesis offered to women with positive results from any screening test. Follow‐up to birth | Routine screening | Prospective cohort | USA | |||
| Marchini 2010* | X | Median 31.3 (18‐45), 19.7% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | Italy | |||
| Marsis 2004 | X | Mean 37.8 (35‐43) | Amniocentesis (unclear in which patients this was conducted) or follow‐up to birth | Screening of patients ≥ 35 years of age | Prospective cohort | Indonesia | |||
| Marsk 2006 | X | X | Mean 38.5 (SD 4.0) for Down's cases, 35.5 (SD 4.0) for controls | Not reported | Routine screening | Case control | Sweden | ||
| Matias 1998 | Median 35 (17‐46) | Fetal karyotyping. In cases where NT above 95th percentile or abnormal ductus venousus flow, follow‐up scan conducted at 14‐16 weeks | High‐risk referral for invasive testing | Prospective cohort | UK and Portugal | ||||
| Matias 2001 | Median 35 (17‐46) | Fetal karyotyping. In cases where NT above 95th percentile or abnormal ductus venousus flow, follow‐up scan conducted at 14‐16 weeks | High‐risk referral for invasive testing | Prospective cohort | Portugal | ||||
| Mavrides 2002 | X | Median 35 (15‐42) | CVS or follow‐up | High‐risk referral for invasive testing | Prospective cohort | UK | |||
| Maxwell 2011 FTS (first trimester screening cohort) | X | Median 31 (14‐48), 24.3% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Australia | |||
| Maymon 2005 | Mean 33.7 (SD 4.9) for Down's cases, 30.3 (SD 4.5) for controls | Amniocentesis (recommended for women with higher risk on first or second trimester testing) or follow‐up to birth | Routine screening | Case control | Israel | ||||
| Maymon 2008 | X | X | Not reported | Karyotyping or follow‐up to birth | Routine screening | Case control | USA | ||
| Merz 2011 | X | Not reported | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | Germany | |||
| Michailidis 2001 | X | Mean 30.1 (13‐50), 21.1% ≥ 35, 11.9% ≥ 37 | Karyotyping in women considered at risk due to index test results, age or family history or those with considerable anxiety (632 women, 8.5%) or follow‐up to birth | Routine screening | Prospective cohort | UK | |||
| Molina 2010 high risk (High‐risk cohort) | X | Mean 32.7 (16.7‐47.5) | CVS | High‐risk referral for invasive testing | Cohort | Spain | |||
| Molina 2010 screening (Screening cohort) | X | Not reported | Karyotyping or follow‐up to birth | Routine screening | Cohort | Spain | |||
| Monni 2005 | X | Median 32 (14‐49) | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Italy | |||
| Montalvo 2005 | X | Mean 31.1 (14‐49), 25.9% ≥35 | Invasive testing offered to women considered high risk from screening results or follow‐up to birth | Routine screening | Prospective cohort | Spain | |||
| Moon 2007 | X | Mean 35.5 (SD 4.8) for Down's cases, 31.7 (SD 3.4) for unaffected pregnancies | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Korea | |||
| Muller 2003 | X | X | Not reported | Invasive testing (offered to women with high NT measurement) or follow‐up to birth | Routine screening | Retrospective cohort | France | ||
| Nicolaides 1992 | X | Median 38 (22‐47) | Fetal karyotyping by amniocentesis (52%) or CVS (48%) | High‐risk referral for invasive testing | Prospective cohort | UK | |||
| Nicolaides 2005 | X | Median 31 (13‐49) | Amniocentesis or CVS (patients considered high risk based on screening). First trimester presence/absence of nasal bone, presence/absence of tricuspid regurgitation or normal/abnormal Doppler studies (patients of intermediate risk on first trimester screening and did not undergo CVS or amniocentesis. With the addition of information from these tests, if adjusted risk was high, CVS was performed). Follow‐up to birth | Routine screening | Prospective cohort | UK | |||
| Niemimaa 2001 | X | X | 17.5% ≥ 35 | Invasive testing (patients considered high risk based on NT screening) or follow‐up to birth. | Routine screening | Prospective cohort | Finland | ||
| Noble 1995 | Median 34 (15‐47), 47% ≥ 35 | Karyotyping performed (27% of women) due to increased NT (14%), advanced maternal age (10%), previous chromosomally abnormal child (0.5%) or parental anxiety (2%). Ultrasound examination at 20 weeks (65% of patients). Follow‐up to birth (9% of women) | Routine screening in a high risk population | Prospective cohort | UK | ||||
| O'Callaghan 2000 | X | Median 32 | CVS, amniocentesis or neonatal karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Australia | |||
| O'Leary 2006 | X | X | Median 31 (14‐47), 20% ≥ 35 | CVS or amniocentesis (women assessed to be high risk on screening) or follow‐up to birth | Routine screening | Prospective cohort | Australia | ||
| Okun 2008 FTS (first trimester screening cohort) | X | Mean 34 | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Canada | |||
| Orlandi 1997 | X | X | Range 15 to 46, 35% ≥ 35 | Not reported | Routine screening | Prospective cohort | Italy | ||
| Orlandi 2003 | X | Median 31.7 (SD 4.0) for Down's cases, 36.5 (SD 4.1) for unaffected pregnancies | CVS or amniocentesis (women considered high risk on screening on the basis of NT and biochemical results, but not on nasal bone screening, or if requested due to age or anxiety) or follow‐up to birth | Routine screening (2 centres) or in referred patients (1 centre) | Prospective cohort | Italy and Netherlands | |||
| Orlandi 2005 | X | Median 30.5 (SD 8.2) | Not reported | Routine screening | Retrospective cohort | Italy | |||
| Otaño 2002 | X | Median 36 (19‐44) | CVS | High‐risk referral for invasive testing | Prospective cohort | Argentina | |||
| Pajkrt 1998 | X | Mean 31.4 (SD 5.7), 24% ≥ 35 | Prenatal karyotyping offered to patients considered high risk or maternal anxiety (conducted in 24%) or follow‐up to birth | Routine screening | Prospective cohort | Netherlands | |||
| Pajkrt 1998a | X | Mean 37.6 (22‐46) | Prenatal karyotyping | High‐risk referral for invasive testing | Consecutive cohort | Netherlands | |||
| Palomaki 2007 FTS (first trimester screening cohort) | Mean 32.3 (SD 4.6) | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Canada | ||||
| Perni 2006 | X | Median 33.0 (IQR 31.0‐36.0) | CVS or amniocentesis. Cytogenetic testing in cases of miscarriage. Follow‐up to birth. | Routine screening | Retrospective cohort | USA | |||
| Prefumo 2005 | X | Median 37 (19‐46) | CVS | High‐risk referral for invasive testing | Prospective cohort | UK | |||
| Prefumo 2006 | X | Mean 31.4 (14.5‐50.2) | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | UK | |||
| Ramos‐Corpas 2006 | X | Mean 30.1 (15‐46) (SD 5.37), 18% ≥ 35 | Invasive testing offered to patients considered high risk at screening (> 1:300) or follow‐up to birth | Routine screening | Prospective cohort | Spain | |||
| Rissanen 2007 | X | 29.5, 17.7% ≥35 | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Finland | |||
| Rozenberg 2002 | X | Median 30.5 (18‐37) | Amniocentesis offered to patients with NT >3mm or serum marker risk was > 1:250, or follow‐up to birth | Routine screening | Prospective cohort | France | |||
| Rozenberg 2007 | X | Mean 30.9 (SD 4.5) | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Canada | |||
| Sahota 2010 | X | X | Median 33.1, 30.1% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | China | ||
| Salomon 2010 | X | Median 30.7 (18.0‐46.3) | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | France | |||
| Santiago 2007 | X | X | Mean 30.6 (14‐46) | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | Spain | ||
| Sau 2001 | X | Mean 28 (SD 5) | Invasive testing (women with high risk on screening) or follow‐up to birth | Routine screening | Prospective cohort | UK | |||
| Schaelike 2009 | X | X | 31.0% ≥35 | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Germany | ||
| Schielen 2006* | X | Median 36.5 (18‐47) | Invasive testing or follow‐up to birth | Routine screening | Retrospective cohort | Netherlands | |||
| Schuchter 2001 | X | Mean 28 (15‐46), 10.7% ≥ 35 | CVS (offered to patients with first trimester NT > 3.5 mm), amniocentesis (offered to patients with first trimester NT 2.5‐3.4 mm, high risk on second trimester serum testing (> 1:250) and those > 35 years) or follow‐up to birth | Routine screening | Retrospective cohort | Austria | |||
| Schuchter 2002 | X | X | 13% > 35 | CVS and amniocentesis (offered to patients with increased risk (> 1:400) at first trimester screening. CVS recommended when NT > 3.5 or when women did not want to wait until the 15th week for amniocentesis), or follow‐up to birth | Routine screening | Prospective cohort | Austria | ||
| Schwarzler 1999 | X | Mean 29.4 (16‐47) | Invasive testing (women considered high risk on screening) or follow‐up to birth | Routine screening | Prospective consecutive cohort | UK | |||
| Scott 2004 | X | X | Median 32 (15‐44), 29% ≥ 35 | Invasive testing or follow‐up to birth | Routine screening | Prospective cohort | Australia | ||
| Sepulveda 2007 | X | X | Median 33 (14‐47), 35.4% ≥ 35 | CVS, amniocentesis, cordocentesis or follow‐up to birth | Routine screening | Prospective cohort | Chile | ||
| Snijders 1998 | X | Median 31 (14‐49) | CVS and amniocentesis (9.6% of women) or follow‐up to birth | Routine screening | Prospective cohort | UK | |||
| Sorensen 2011 | X | Median 34 (23‐44) for Down's cases; mean 30.4 (16‐45), 16.5% ≥ 35 for unaffected pregnancies | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | Denmark | |||
| Spencer 1999 | X | X | X | Median 38 (19‐46) for Down's cases, 36 (15‐47) for controls | Invasive testing (high‐risk women) or follow‐up to birth | Routine screening | Case control | UK | |
| Spencer 2002 | Median 36 (20‐44) for Down's cases, 30 (16‐41) for controls | Not reported | Routine screening | Case control | UK | ||||
| Spencer 2008 | X | Median 35.8 for Down's cases, 29.3 for controls | Karyotyping or follow‐up to birth | Routine screening | Case control | Denmark | |||
| Stenhouse 2004 | X | Median 32 (14‐45), 27% ≥ 35 | Invasive testing offered to women with screening risk of > 1:250 or follow‐up to birth | Routine screening | Prospective cohort | UK | |||
| Strah 2008 | X | Median 28.6 (15‐42) | Karyotyping or follow‐up to birth | Routine screening | Cohort | Slovenia | |||
| Theodoropoulos 1998 | X | Median 29 (16‐48), 7.8% ≥ 37 | CVS or amniocentesis or follow‐up to birth. Unclear reference standard in cases of intrauterine death, miscarriages and terminations. | Routine screening | Prospective cohort | Greece | |||
| Thilaganathan 1999 | X | Mean 29 (15‐45) | CVS (offered to patients considered high risk on screening) or follow‐up to birth | Routine screening | Prospective cohort | UK | |||
| Timmerman 2010 | Mean 34.5 (19‐45) | Karyotyping or follow‐up to birth | Routine screening | Prospective cohort | Netherlands | ||||
| Torring 2010 | X | Mean 35 for Down's cases, 31 for controls | Karyotyping or follow‐up to birth | Routine screening | Case control | Denmark | |||
| Vadiveloo 2009 | X | Median 33.1, 36.9% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | UK | |||
| Valinen 2007 | X | Mean 29.6, 18.6% ≥ 35 | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | Finland | |||
| Viora 2003 | Median 32 (18‐47) | CVS or follow‐up to birth | Routine screening | Prospective cohort | Italy | ||||
| Wald 2003 | X | X | X | Not reported | Invasive testing (following second trimester screening) or follow‐up to birth | Routine screening | Case control | UK and Austria | |
| Wapner 2003* | X | X | Mean 35 (SD 4.6), 50% ≥ 35 | Invasive testing. Miscarriage with cytogenetic testing. Follow‐up to birth | Routine screening | Prospective cohort | USA | ||
| Wax 2009 | X | Mean 36.7 (SD 3.2) | Karyotyping or follow‐up to birth | Routine screening | Retrospective cohort | USA | |||
| Wojdemann 2005 | X | X | Mean 29, 10.8% ≥ 35 | Invasive testing (in cases of increased risk) or follow‐up to birth | Referrals for screening | Prospective cohort | Denmark | ||
| Wortelboer 2009 | X | Median 34.9 (15‐48) | Karyotyping or follow‐up to birth | Routine screening | Cohort | Netherlands | |||
| Wright 2008 | X | Median 35.2 (16‐52) | Karyotyping or follow‐up to birth | Routine screening | Cohort | UK | |||
| Wright 2010 | X | Median 31.9 (IQR 27.7‐35.8) | Karyotyping or follow‐up to birth | Routine screening | Cohort | UK, Denmark and Cyprus | |||
| Zoppi 2001 | X | Median 33 (14‐48) | Amniocentesis, CVS or follow‐up to birth | Routine screening | Prospective cohort | Italy |
*The study provided data for the subset of women with maternal age of 35 or more.
X indicates that the test was evaluated in the study.
CVS = chorionic villus sampling; IQR = interquartile range; SD = standard deviation.