The chances to achieve pregnancy after retrieving >15 oocytes are not good, probably because of bad effect on the endometrium (uterine inner lining). Therefore, in most such cases the investigators prefer to freeze all embryos, and transfer in a thaw cycle. With the introduction of oocyte vitrification (very fast cooling) technology, a new option emerged: to freeze un-fertilized eggs, to be fertilized and used later in a thaw cycle.
The purpose of this study is to compare the outcome of these two approaches.
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Exclusion Criteria: