Experience with the elective transfer of two embryos under the conditions of the german embryo protection law: results of a retrospective data analysis of 2573 transfer cycles.

The German embryo protection law (Embryonenschutzgesetz, ESchG) does not allow embryo selection. Therefore, only as many oocytes at the pronuclear stage (PN), as are planned to be transferred, are allowed to be cultured. It is not known whether, under these conditions, it is possible to reduce the number of embryos for transfer without a corresponding reduction of the overall pregnancy rate (PR). We retrospectively analysed 2573 consecutive transfer cycles following either in-vitro fertilization (IVF) or IVF/intracytoplasmic sperm injection. Out of these cycles, 234, 329 and 792 were performed with one, two, and three embryos respectively, because only that number was available (non-elective transfer). Another 123 and 1095 transfer cycles were performed with two and three embryos, respectively, which were selected from a higher number of PN oocytes (elective transfer). The clinical ongoing PR were 3.9, 9.1 and 17.7% respectively for the groups with non-elective transfer of 1, 2 and 3 embryos, and 22.0 and 22.5% for the groups with elective transfers with two and three embryos, respectively. There was no statistically significant difference in PR between the two elective embryo transfer groups up to the age of 40 years. The multiple pregnancy rate was reduced by 7.9%. The reduction of the number of embryos transferred from three to two can be performed even under the conditions of the ESchG without an effect on the overall PR.