Professor Ricardo Felberbaum will warn participants at the European Society of Human Reproduction and Embryology annual conference that other countries in Europe should take heed of the German experience when formulating their own legislation on embryo selection, storage and implantation.
Since January 1991, under German law a maximum of three embryos can be transferred to a woman's uterus, but only as many female eggs (oocytes) can be fertilized as planned to be transferred, and then they all have to be transferred in one go, regardless of quality, because embryo selection and storage by freezing is forbidden. Only freezing of oocytes in the pronuclear stage is allowed, which means that selection has to be performed at that stage of development and not later.
These laws were thought to guarantee a low incidence of multiple births, but Prof Felberbaum said that, in fact, this goal was not achieved.
He studied data from 108 IVF centres on 75,086 treatment cycles in 2001. Out of 9,648 children born after ART 62% (5,969) were singletons, 34% (3,326) were twins and 3.6% (353) were triplets. There was a strong correlation between the number of embryos transferred and the incidence of multiple pregnancies. In women under 35, 24% of pregnancies were twins after the transfer of two embryos, and when three embryos were transferred 28% were twins and just over 5% were triplets.
The quality of the embryos transferred dramatically affected pregnancy rates: when two, high-quality embryos were transferred there was an overall pregnancy rate of 32%, but when two, low-quality embryos were transferred the overall pregnancy rate dropped to just 13%.
Prof. Felberbaum told a news briefing today (Monday 30 June): "Ger
Contact: Emma Mason
European Society for Human Reproduction and Embryology