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University of Western Australia and Fertility Specialists of Western Australia has found that women undergoing IVF who have had embryos fail to implant have more success using frozen ones than fresh ones. One in ten women who undergo IVF experienced recurrent unsuccessful embryo implantation.
Professor Roger Hart from UWA’s Division of Obstetrics and Gynaecology, and Fertility Specialists of Western Australia, said the researchers studied patients who underwent 140 IVF cycles, to identify success rates by comparing the two different types of transfers (frozen versus fresh) with recurring unsuccessful cycles. They discovered that the birth rate for frozen and thawed embryos was 39 per cent, compared to 20 per cent for fresh embryos.
The researchers excluded any correctable factors present within the woman that may have limited the embryo implanting and then undertook preimplantation genetic screening of embryos on day three to ensure there were no abnormalities. The results shows that a frozen embryo implantation is more successful than transferring the embryo straight after the biopsy in a fresh IVF cycle, as the environment within the uterus is more ‘normal’ in a subsequent natural cycle, than during an IVF cycle where the hormone levels are very high.
The success of the transfer was less if the woman was significantly overweight, if there were a lower number of cells present within the embryo at the time of biopsy and if the pregnancy hormone level was lower at the time of the pregnancy test. Women under the age of 35 also have higher success rates. Compared to unbiopsied embryos, biopsing an embryo after 3 days of growth could impair growth, which suggested the more advanced an embryo was at the time of biopsy, the more it would withstand the biopsy process.
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