title: Number of transferred embryos: how to reduce multiple pregnancies.
abstract: Because the diagnostic tools for predicting whether an early cleavage stage embryo can lead to a viable pregnancy are still elusive, transfer of more than one embryo remains quite common. However, the only way to reduce multiple pregnancies, considered as the main adverse effect of assisted reproductive technology, is to transfer a single embryo. In countries such as Switzerland and Germany, the law allows cryopreservation only at the 2-pronuclear stage. This restricts considerably the possibility of selecting the embryos to be transferred. Therefore, a good cryopreservation program at the 2-pronuclear stage is an essential tool to optimize the efficiency of in vitro fertilization (IVF). We therefore recommend the Cumulated Singleton Delivery Rate (CUSIDERA) as a measure of standard IVF efficiency. This rate averages approximately 23.5% when calculated over the last 10 years in our unit and reaches a value above 35% for patients with more than 10 zygotes. Elective single-embryo transfers and the decrease of iatrogenic multiple pregnancies in IVF remain dependent on better prognostic tools for the appropriate selection of patients, gametes, and zygotes.
authors.affiliation: Unité de Médecine de la Reproduction, Maternité, CHUV, CH-1011 Lausanne, Switzerland. marc.germond@chuv.hospvd.ch
authors.forename: Marc
authors.initials: M
authors.lastname: Germond
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Primi
authors.forename: Françoise
authors.initials: F
authors.lastname: Urner
authors.forename: Alain
authors.initials: A
authors.lastname: Chanson
authors.forename: Daniel
authors.initials: D
authors.lastname: Wirthner
authors.forename: Alfred
authors.initials: A
authors.lastname: Senn
mesh_terms: D015925:Cryopreservation / Q000379:methods*; D004624:Embryo Transfer / Q000592:standards; D005260:Female; D005307:Fertilization in Vitro / Q000331:legislation & jurisprudence / Q000379:methods* / Q000592:standards; D006801:Humans; D009099:Multiple Birth Offspring; D011247:Pregnancy; D011248:Pregnancy Complications / Q000517:prevention & control*; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D013557:Switzerland; D017388:Zygote Intrafallopian Transfer / Q000379:methods*