Abstract
In the past few decades, the number of multiple pregnancies has increased significantly. Advanced maternal age, use of ovarian stimulation and use of IVF are all responsible for this. A multiple pregnancy carries excess maternal and neonatal risks and is associated with undesired extra health care expenses as well. Up to 1/3 of the pregnancies following IVF are multiple gestations; most being twins. The best way to minimize the risk of twins is to transfer a single embryo only. The majority of the embryos do not implant however and most clinics routinely transfer 2 or even more embryos to maintain high IVF success rates (pregnancy rates). A high success rate despite the transfer of fewer, preferably a single embryo could be maintained if we had better tools to identify the embryo with the highest implantation potential. Current selection criteria based on the cleavage rate and morphology of the embryo are not particularly effective for this. The past decade has seen a lot of research aiming to screen the embryos based on various properties. This review will discuss the perinatal outcome of IVF multiples, available screening tools for embryo selection and the current status of the development of new tools.
Keywords: IVF, embryo morphology, metabolomics, perinatal outcome, preimplantation genetic screening, proteomics , single embryo transfer, time lapse monitoring
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