title: Quality of additional embryos transferred on pregnancy outcomes in IVF: predictions using a mathematical approach.
abstract: This study assessed the influence of adding embryos with different embryo quality on pregnancy rate and multiple pregnancy rate (MPR). The study included 1891 IVF transfers performed at two centres with different embryo transfer policies. Pregnancy rate and MPR were analysed following three models and then including embryo quality. A predictive mathematical model and two scatter plots were constructed. The model based on embryo independence was incompatible with the observed data, while both the ground and collaborative models provided excellent fits. The collaborative model, however, predicted multiple pregnancies, especially triplets, more accurately. Transfer of additional embryos, irrespective of embryo quality, always increased pregnancy rate and MPR. When implantation rate was low, there was a marked increase in pregnancy rate but only a relatively small increase in MPR. In contrast, with higher implantation rates, the increase in pregnancy rate was mainly due to the increase in MPR, with the same singleton pregnancy rate. Transfer of additional embryos, irrespective of embryo quality, follows a collaborative pattern and always results in an increase in pregnancy rate and MPR. The scatter plots accurately predicted the influence of the different combinations of number and embryo quality on pregnancy rate and MPR.
authors.affiliation: Department of Obstetrics and Gynecology, Hospital de Cruces, Baracaldo, Vizcaya, Spain; Instituto Valenciano de Infertilidad, Lejona, Vizcaya, Spain; University of the Basque Country, Lejona, Vizcaya, Spain.
authors.forename: Roberto
authors.initials: R
authors.lastname: Matorras
authors.affiliation: Department of Obstetrics and Gynecology, Hospital de Cruces, Baracaldo, Vizcaya, Spain.
authors.forename: Borja
authors.initials: B
authors.lastname: Otero
authors.affiliation: Department of Obstetrics and Gynecology, Hospital de Cruces, Baracaldo, Vizcaya, Spain.
authors.forename: Rosario
authors.initials: R
authors.lastname: Mendoza
authors.affiliation: Department of Obstetrics and Gynecology, Hospital de Cruces, Baracaldo, Vizcaya, Spain. Electronic address: antonia.expositonavarro@osakidetza.net.
authors.forename: Antonia
authors.initials: A
authors.lastname: Expósito
authors.affiliation: Instituto Valenciano de Infertilidad, Lejona, Vizcaya, Spain.
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: De Pablo
authors.affiliation: Instituto Valenciano de Infertilidad, Lejona, Vizcaya, Spain.
authors.forename: Zaloa
authors.initials: Z
authors.lastname: Larreategui
authors.affiliation: Instituto Valenciano de Infertilidad, Lejona, Vizcaya, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Ayerdi
authors.affiliation: Faculty of Sciences, University of Cantabria, Cantabria, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Matorras
mesh_terms: D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D015233:Models, Statistical; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate
keywords: embryo quality; pregnancy rate; scatter plot