I. R. Merkatz, H. M. Nitowsky, J. N. Macri, and W. E. Johnson, An association between low maternal serum alpha-fetoprotein and fetal chromosomal abnormalities, Am J Obstet Gynecol. 1 avr, vol.148, issue.7, pp.886-94, 1984.

M. H. Bogart, M. R. Pandian, and O. W. Jones, Abnormal maternal serum chorionic gonadotropin levels in pregnancies with fetal chromosome abnormalities, vol.7, pp.623-653, 1987.

J. N. Macri, K. Spencer, D. Aitken, K. Garver, P. D. Buchanan et al.,

, First-trimester free beta (hCG) screening for Down syndrome, Prenat Diagn. juill, vol.13, issue.7, pp.557-62, 1993.

J. A. Canick, G. J. Knight, G. E. Palomaki, J. E. Haddow, H. S. Cuckle et al.,

, Low second trimester maternal serum unconjugated oestriol in pregnancies with Down's syndrome, Br J Obstet Gynaecol. avr, vol.95, issue.4, pp.330-333, 1988.

K. Spencer, E. J. Coombes, A. S. Mallard, and A. M. Ward, Free beta human choriogonadotropin in Down's syndrome screening: a multicentre study of its role compared with other biochemical markers, Ann Clin Biochem. sept, vol.29, pp.506-524, 1992.

J. N. Macri, K. Spencer, K. Garver, P. D. Buchanan, B. Say et al.,

, Maternal serum free beta hCG screening: results of studies including 480 cases of Down syndrome, Prenat Diagn. févr, vol.14, issue.2, pp.97-103, 1994.

H. Cuckle, Integrating antenatal Down's syndrome screening, Curr Opin Obstet Gynecol. avr, vol.13, issue.2, pp.175-81, 2001.

K. H. Nicolaides, M. L. Brizot, and R. J. Snijders, Fetal nuchal translucency: ultrasound screening for fetal trisomy in the first trimester of pregnancy, Br J Obstet Gynaecol. sept, vol.101, issue.9, pp.782-788, 1994.

P. P. Pandya, R. J. Snijders, and S. P. Johnson,

. Kh, Screening for fetal trisomies by maternal age and fetal nuchal translucency thickness at 10 to 14 weeks of gestation, Br J Obstet Gynaecol. déc, vol.102, issue.12, pp.957-62, 1995.

R. J. Snijders, P. Noble, N. Sebire, A. Souka, and K. H. Nicolaides, UK multicentre project on assessment of risk of trisomy 21 by maternal age and fetal nuchaltranslucency thickness at 10-14 weeks of gestation. Fetal Medicine Foundation First Trimester Screening Group, Lancet Lond Engl. 1 août, vol.352, issue.9125, pp.343-349, 1998.

R. A. Kadir and D. L. Economides, The effect of nuchal translucency measurement on second-trimester biochemical screening for Down's syndrome

, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. avr, vol.9, issue.4, pp.244-251, 1997.

B. Thilaganathan, A. Slack, and N. C. Wathen, Effect of first-trimester nuchal translucency on second-trimester maternal serum biochemical screening for Down's syndrome, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. oct, vol.10, issue.4, pp.261-265, 1997.

F. Audibert, M. Dommergues, C. Benattar, J. Taieb, and J. C. Thalabard,

R. , Screening for Down syndrome using first-trimester ultrasound and secondtrimester maternal serum markers in a low-risk population: a prospective longitudinal study, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. juill, vol.18, issue.1, pp.26-31, 2001.

P. Rozenberg, L. Malagrida, H. Cuckle, and I. Durand-zaleski,

F. , Down's syndrome screening with nuchal translucency at 12(+0)-14(+0) weeks and maternal serum markers at 14(+1)-17(+0) weeks: a prospective study, Hum Reprod Oxf Engl. avr, vol.17, issue.4, pp.1093-1101, 2002.

K. Spencer, J. N. Macri, D. A. Aitken, and J. M. Connor, Free beta-hCG as firsttrimester marker for fetal trisomy, Lancet Lond Engl. 13 juin, vol.339, issue.8807, p.1480, 1992.

N. J. Wald, A. Kennard, and A. K. Hackshaw, First trimester serum screening for Down's syndrome, Prenat Diagn. déc, vol.15, issue.13, pp.1227-1267, 1995.

P. A. Hurley, R. H. Ward, B. Teisner, R. K. Iles, M. Lucas et al., Serum PAPP-A measurements in first-trimester screening for Down syndrome, Prenat Diagn, vol.13, issue.10, pp.903-911, 1993.

B. Brambati, M. C. Macintosh, B. Teisner, S. Maguiness, and K. Shrimanker,

A. Lanzani, Low maternal serum levels of pregnancy associated plasma protein A (PAPP-A) in the first trimester in association with abnormal fetal karyotype, Br J Obstet Gynaecol. avr, vol.100, issue.4, pp.324-330, 1993.

Y. M. Lo, N. Corbetta, P. F. Chamberlain, V. Rai, I. L. Sargent et al.,

, Presence of fetal DNA in maternal plasma and serum, Lancet Lond Engl. 16 août, vol.350, issue.9076, pp.485-492, 1997.

Y. M. Lo, M. S. Tein, T. K. Lau, C. J. Haines, T. N. Leung et al.,

, Quantitative analysis of fetal DNA in maternal plasma and serum: implications for noninvasive prenatal diagnosis, Am J Hum Genet. avr, vol.62, issue.4, pp.768-75, 1998.

Y. Ohashi, N. Miharu, H. Honda, O. Samura, and K. Ohama, Correlation of fetal DNA and human chorionic gonadotropin concentrations in second-trimester maternal serum, Clin Chem. févr, vol.48, issue.2, pp.386-394, 2002.

Y. M. Lo, J. Zhang, T. N. Leung, T. K. Lau, A. M. Chang et al., Rapid clearance of fetal DNA from maternal plasma, Am J Hum Genet. janv, vol.64, issue.1, pp.218-242, 1999.

J. Costa, A. Benachi, and E. Gautier, New strategy for prenatal diagnosis of X-linked disorders, N Engl J Med. 9 mai, vol.346, issue.19, p.1502, 2002.

Y. M. Lo, N. M. Hjelm, C. Fidler, I. L. Sargent, M. F. Murphy et al., Prenatal diagnosis of fetal RhD status by molecular analysis of maternal plasma, N Engl J Med. 10 déc, vol.339, issue.24, pp.1734-1742, 1998.

M. M. Gil, V. Accurti, B. Santacruz, M. N. Plana, and K. H. Nicolaides, Analysis of cellfree DNA in maternal blood in screening for aneuploidies: updated meta-analysis

, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. sept, vol.50, issue.3, pp.302-316, 2017.

S. Taylor-phillips, K. Freeman, J. Geppert, A. Agbebiyi, O. A. Uthman et al.,

J. , Accuracy of non-invasive prenatal testing using cell-free DNA for detection of Down, Edwards and Patau syndromes: a systematic review and meta-analysis, BMJ Open. 18 janv, vol.6, issue.1, p.10002, 2016.

M. Badeau, C. Lindsay, J. Blais, L. Nshimyumukiza, Y. Takwoingi et al.,

S. , Genomics-based non-invasive prenatal testing for detection of fetal chromosomal aneuploidy in pregnant women, Cochrane Database Syst Rev, vol.10, p.11767, 2017.

A. Benachi, A. Letourneau, P. Kleinfinger, M. Senat, E. Gautier et al., Cell-free DNA analysis in maternal plasma in cases of fetal abnormalities detected on ultrasound examination, Obstet Gynecol. juin, vol.125, issue.6, pp.1330-1337, 2015.

R. Chiu, K. Chan, Y. Gao, V. Lau, W. Zheng et al.,

, Noninvasive prenatal diagnosis of fetal chromosomal aneuploidy by massively parallel genomic sequencing of DNA in maternal plasma, Proc Natl Acad Sci U S A. 23 déc, vol.105, issue.51, pp.20458-63, 2008.

D. W. Bianchi, L. D. Platt, J. D. Goldberg, A. Z. Abuhamad, A. J. Sehnert et al., Genome-wide fetal aneuploidy detection by maternal plasma DNA sequencing, Obstet Gynecol. mai, vol.119, issue.5, pp.890-901, 2012.

S. Dan, W. Wang, J. Ren, Y. Li, H. Hu et al., Clinical application of massively parallel sequencing-based prenatal noninvasive fetal trisomy test for trisomies 21 and 18 in 11,105 pregnancies with mixed risk factors, Prenat Diagn. déc, vol.32, issue.13, pp.1225-1257, 2012.

M. Ehrich, C. Deciu, T. Zwiefelhofer, J. A. Tynan, L. Cagasan et al.,

, Noninvasive detection of fetal trisomy 21 by sequencing of DNA in maternal blood: a study in a clinical setting, Am J Obstet Gynecol. mars, vol.204, issue.3, pp.205-206, 2011.

R. P. Porreco, T. J. Garite, K. Maurel, B. Marusiak, O. Network et al., Noninvasive prenatal screening for fetal trisomies 21, 18, 13 and the common sex chromosome aneuploidies from maternal blood using massively parallel genomic sequencing of DNA, Am J Obstet Gynecol, vol.211, issue.4, pp.365-366, 2014.

G. E. Palomaki, E. M. Kloza, G. M. Lambert-messerlian, and J. E. Haddow,

. Lm and M. Ehrich, DNA sequencing of maternal plasma to detect Down syndrome: an international clinical validation study, Genet Med Off J Am Coll Med Genet, vol.13, issue.11, pp.913-933, 2011.

L. Poon, T. Musci, K. Song, A. Syngelaki, and K. H. Nicolaides, Maternal plasma cell-free fetal and maternal DNA at 11-13 weeks' gestation: relation to fetal and maternal characteristics and pregnancy outcomes, Fetal Diagn Ther, vol.33, issue.4, pp.215-238, 2013.

D. W. Bianchi, R. P. Rava, A. J. Sehnert, G. Fairbrother, J. S. Musci et al., Clinical experience of noninvasive prenatal testing with cell-free DNA for fetal trisomies 21, 18, and 13, in a general screening population, N Engl J Med. 7 août, vol.371, issue.6, pp.580-583, 2013.

M. M. Gil, M. S. Quezada, B. Bregant, M. Ferraro, and K. H. Nicolaides,

, Implementation of maternal blood cell-free DNA testing in early screening for aneuploidies, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. juill, vol.42, issue.1, pp.34-40, 2013.

J. Costa, A. Letourneau, R. Favre, L. Bidat, J. Belaisch-allart et al.,

M. , Cell-free fetal DNA versus maternal serum screening for trisomy 21 in pregnant women with and without assisted reproduction technology: a prospective interventional study, Genet Med Off J Am Coll Med Genet. 1 mars, 2018.

C. Prunet, F. Goffinet, and B. Blondel, Prise en charge et santé périnatale en cas de grossesse gémellaire : situation en 2010 et évolution récente en France, J Gynécologie Obstétrique Biol Reprod. févr, vol.44, issue.2, pp.184-93, 2015.

P. Enquête-nationale, Les naissances et les établissements, situation et évolution depuis 2010 -Ministère des Solidarités et de la Santé, 2016.

P. Prats, I. Rodríguez, C. Comas, and B. Puerto, Systematic review of screening for trisomy 21 in twin pregnancies in first trimester combining nuchal translucency and biochemical markers: a meta-analysis, Prenat Diagn, vol.34, issue.11, pp.1077-83, 2014.

A. Garchet-beaudron, S. Dreux, N. Leporrier, J. Oury, F. Muller et al., Second-trimester Down syndrome maternal serum marker screening: a prospective study of 11 040 twin pregnancies, Prenat Diagn. déc, vol.28, issue.12, pp.1105-1114, 2008.

H. N. Madsen, S. Ball, D. Wright, N. Tørring, O. B. Petersen et al., A reassessment of biochemical marker distributions in trisomy 21-affected and unaffected twin pregnancies in the first trimester, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. janv, vol.37, issue.1, pp.38-47, 2011.

C. Giorgetti, V. Meerschaut, F. , D. Roo, C. Saunier et al.,

D. Hairion, Multivariate analysis identifies the estradiol level at ovulation triggering as an independent predictor of the first trimester pregnancy-associated plasma protein-A level in IVF/ICSI pregnancies, Hum Reprod Oxf Engl, vol.28, issue.10, pp.2636-2678, 2013.

J. Bellver, C. Casanova, N. Garrido, C. Lara, J. Remohí et al.,

, Additive effect of factors related to assisted conception on the reduction of maternal serum pregnancy-associated plasma protein A concentrations and the increased false-positive rates in first-trimester Down syndrome screening, Fertil Steril, vol.100, issue.5, pp.1314-1334, 2013.

J. Vink, K. Fuchs, D. 'alton, and M. E. , Amniocentesis in twin pregnancies: a systematic review of the literature, Prenat Diagn. mai, vol.32, issue.5, pp.409-425, 2012.

K. Agarwal and Z. Alfirevic, Pregnancy loss after chorionic villus sampling and genetic amniocentesis in twin pregnancies: a systematic review, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. août, vol.40, issue.2, pp.128-162, 2012.

, Society for Maternal-Fetal Medicine (SMFM) Publications Committee. Electronic address: esteele@smfm.org. SMFM Statement: clarification of recommendations regarding cell-free DNA aneuploidy screening, Committee Opinion Summary No, vol.640, issue.3, pp.753-757, 2015.

M. M. Gil, R. Revello, L. C. Poon, R. Akolekar, and K. H. Nicolaides, Clinical implementation of routine screening for fetal trisomies in the UK NHS: cell-free DNA test contingent on results from first-trimester combined test, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. janv, vol.47, issue.1, pp.45-52, 2016.

D. Oepkes, G. Page-christiaens, C. J. Bax, M. N. Bekker, and C. M. Bilardo,

. Emj, Trial by Dutch laboratories for evaluation of non-invasive prenatal testing. Part I-clinical impact, Prenat Diagn. déc, vol.36, issue.12, 2016.

, Fetal Diagn Ther, vol.35, issue.3, pp.204-215, 2014.

X. Huang, J. Zheng, M. Chen, Y. Zhao, C. Zhang et al., Noninvasive prenatal testing of trisomies 21 and 18 by massively parallel sequencing of maternal plasma DNA in twin pregnancies: Sequencing-based prenatal noninvasive fetal trisomy test in twin pregnancies, Prenat Diagn. avr, vol.34, issue.4, pp.335-375, 2014.

S. Grömminger, E. Yagmur, S. Erkan, S. Nagy, U. Schöck et al.,

, Fetal Aneuploidy Detection by Cell-Free DNA Sequencing for Multiple Pregnancies and Quality Issues with Vanishing Twins, J Clin Med. 25 juin, vol.3, issue.3, pp.679-92, 2014.

E. Bevilacqua, M. M. Gil, K. H. Nicolaides, E. Ordoñez, V. Cirigliano et al., Performance of screening for aneuploidies by cell-free DNA analysis of maternal blood in twin pregnancies, Ultrasound Obstet Gynecol. janv, vol.45, issue.1, pp.61-67, 2015.

Y. Tan, Y. Gao, G. Lin, M. Fu, X. Li et al., Noninvasive prenatal testing (NIPT) in twin pregnancies with treatment of assisted reproductive techniques (ART) in a single center, Prenat Diagn. juill, vol.36, issue.7, pp.672-681, 2016.

L. Sarno, R. Revello, E. Hanson, R. Akolekar, and K. H. Nicolaides, Prospective screening for trisomies by cell-free DNA testing of maternal blood in first trimester twin pregnancies, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. 11 mars, 2016.

L. Fosler, P. Winters, K. W. Jones, K. J. Curnow, A. J. Sehnert et al.,

, Aneuploidy Screening Using Noninvasive Prenatal Testing in Twin Pregnancies

, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol. 19 mai, 2016.

T. Y. Leung, J. Qu, G. Liao, P. Jiang, Y. Cheng et al.,

, Noninvasive twin zygosity assessment and aneuploidy detection by maternal plasma DNA sequencing: Noninvasive twin zygosity and aneuploidy detection

, Prenat Diagn. juill, vol.33, issue.7, pp.675-81, 2013.

L. Conte, G. Letourneau, A. Jani, J. Kleinfinger, P. Lohmann et al., Cell-free fetal DNA analysis in maternal plasma as a screening test for trisomy 21, 18 and 13 in twin pregnancies, Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol, 2017.

T. J. Jensen, T. Zwiefelhofer, R. C. Tim, ?. D?akula, S. K. Kim et al., High-throughput massively parallel sequencing for fetal aneuploidy detection from maternal plasma, PloS One, vol.8, issue.3, p.57381, 2013.

S. K. Kim, G. Hannum, J. Geis, J. Tynan, G. Hogg et al., Determination of fetal DNA fraction from the plasma of pregnant women using sequence read counts, Prenat Diagn. août, vol.35, issue.8, pp.810-815, 2015.

J. A. Canick, E. M. Kloza, G. M. Lambert-messerlian, J. E. Haddow, M. Ehrich et al., DNA sequencing of maternal plasma to identify Down syndrome and other trisomies in multiple gestations, Prenat Diagn. août, vol.32, issue.8, pp.730-734, 2012.

J. Qu, T. Y. Leung, P. Jiang, G. Liao, Y. Cheng et al.,

, Noninvasive Prenatal Determination of Twin Zygosity by Maternal Plasma DNA Analysis, Clin Chem. 2 janv, vol.59, issue.2, pp.427-462, 2013.

H. C. Fan and S. R. Quake, Sensitivity of Noninvasive Prenatal Detection of Fetal Aneuploidy from Maternal Plasma Using Shotgun Sequencing Is Limited Only by Counting Statistics, Bridger JM, éditeur. PLoS ONE. 3 mai, vol.5, issue.5, p.10439, 2010.

D. J. Amor, J. X. Xu, J. L. Halliday, I. Francis, D. L. Healy et al.,

, Pregnancies conceived using assisted reproductive technologies (ART) have low levels of pregnancy-associated plasma protein-A (PAPP-A) leading to a high rate of false-positive results in first trimester screening for Down syndrome, Hum Reprod Oxf Engl. juin, vol.24, issue.6, pp.1330-1338, 2009.

T. J. Lee, D. L. Rolnik, M. A. Menezes, A. C. Mclennan, S. Da et al., Cellfree fetal DNA testing in singleton IVF conceptions, Hum Reprod Oxf Engl. 1 avr, vol.33, issue.4, pp.572-580, 2018.

, Annexe II : Formulaire de recueil des issues de grossesses envoyé aux prescripteurs

V. I. Annexe, Information sur les conditions de recueil et d'envoi des échantillons par le laboratoire CERBA