Review Twin pregnancies: guidelines for clinical practice from the French College of Gynaecologists and Obstetricians (CNGOF) Christophe Vayssie `re a,b, *, Guillaume Benoist c , Be ´ atrice Blondel d , Philippe Deruelle e , Romain Favre f , Denis Gallot g , Paul Jabert h , Didier Lemery g , Olivier Picone i , Jean-Claude Pons j , Francis Puech g , Edwin Quarello k , Laurent Salomon l , Thomas Schmitz m , Marie-Victoire Senat n , Loı¨c Sentilhes o , Agnes Simon p , Julien Stirneman l , Franc ¸oise Vendittelli g , Norbert Winer q , Yves Ville l a Service de Gyne ´cologie-Obste ´trique, Ho ˆpital Paule de Viguier, CHU Toulouse 31059 Toulouse, France b Inserm U1027, Unite ´ de Recherche en Epide ´miologie Pe ´rinatale, De ´veloppement et Sante ´ de l’Enfant, 31000 Toulouse, France c Service de Gyne ´cologie-Obste ´trique, CHU Caen 14000 Caen, France d Inserm U953, Unite ´ de recherche Epide ´miologique de Recherche en Epide ´miologie sur la sante ´ pe ´rinatale et la sante ´ des femmes et des enfants, 94805 Villejuif, France e Service de Gyne ´cologie-Obste ´trique, Ho ˆpital Jeanne-de-Flandre, CHRU Lille F-59037 Lille cedex, France f Service de Gyne ´cologie-Obste ´trique, CMCO, F-67303 Strasbourg, France g Service de Gyne ´cologie-Obste ´trique, CHU Clermont-Ferrand, 63000 Clermont-Ferrand, France h Fe ´de ´ration Jumeau et plus 75009 Paris, France i Service de Gyne ´cologie-Obste ´trique, Hoˆpital Antoine Be ´cle `re AP-HP, 92140 Clamart, France j Service de Gyne ´cologie-Obste ´trique, CHU Grenoble, 38043 Grenoble, France k Service de Gyne ´cologie-Obste ´trique, Hoˆpital Saint-Joseph, F-13285 Marseille, France l Service de Gyne ´cologie-Obste ´trique, Hoˆpital Necker-Enfants Malades, APHP 75015 Paris, France m Service de Gyne ´cologie-Obste ´trique, Maternite ´ Port-Royal, CHU Cochin AP-HP 75014 Paris, France n Service de Gyne ´cologie-Obste ´trique, CHU Le Kremlin-Biceˆtre AP-HP, 94275 Le Kremlin-Biceˆtre, France o Service de Gyne ´cologie-Obste ´trique, CHU Angers, 49033 Angers, France p Service de Gyne ´cologie-Obste ´trique, CHU Saint-Antoine, Paris, France q Service de Gyne ´cologie-Obste ´trique, CHU Nantes, 44093 Nantes, France European Journal of Obstetrics & Gynecology and Reproductive Biology 156 (2011) 12–17 ARTICLE INFO Article history: Received 12 December 2010 Accepted 31 December 2010 Key words: Twin pregnancy Chorionicity Monochorionic Twin–twin transfusion syndrome Prematurity Internal version Guidelines ABSTRACT The rate of twin deliveries in 2008 was 15.6 per 1000 in France, an increase of approximately 80% since the beginning of the 1970s. It is recommended that chorionicity be diagnosed as early as possible in twin pregnancies (Professional Consensus). The most relevant signs (close to 100%) are the number of gestational sacs between 7 and 10 weeks and the presence of a lambda sign between 11 and 14 weeks (Professional Consensus). In twin pregnancies, nuchal translucency is the best parameter for evaluating the risk of aneuploidy (Level B). The routine use of serum markers during the first or the second trimester is not recommended (Professional Consensus). In the case of a choice about sampling methods, chorionic villus sampling is recommended over amniocentesis (Professional Consensus). Monthly follow-up by a gynaecologist–obstetrician in an appropriate facility is recommended for dichorionic pregnancies (Professional Consensus). A monthly ultrasound examination including an estimation of fetal weight and umbilical artery Doppler is recommended (Professional Consensus). It is recommended to plan delivery of uncomplicated dichorionic diamniotic twin pregnancies from 38 weeks and before 40 weeks (Level C). Monthly prenatal consultations and twice-monthly ultrasound are recommended for monochorionic twins (Professional Consensus). It is reasonable to consider delivery from 36 weeks but before 38 weeks + 6 days, with intensified monitoring during that time (Professional Consensus). Prenatal care of monochorionic pregnancies must be provided by a physician working in close collaboration with a facility experienced in the management of this type of pregnancy and its complications (Professional Consensus). The increased risk of maternal complications and the high rate of medical interventions justify the immediate and permanent availability of a gynaecologist–obstetrician with experience in the vaginal * Corresponding author at: Service de Gyne ´ cologie-Obste ´ trique, Ho ˆ pital Paule de Viguier, CHU Toulouse 31059 Toulouse, France. Tel.: +33 567771379; fax: +33 567771219. E-mail address: christophe.vayssiere@gmail.com (C. Vayssie ` re). Contents lists available at ScienceDirect European Journal of Obstetrics & Gynecology and Reproductive Biology journal homepage: www.elsevier.com/locate/ejogrb 0301-2115/$ – see front matter ß 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejogrb.2010.12.045