A major study by Finish scientists just published in Human Reproduction magazine, brings reassurance on the risks, or lack of them, between frozen IVF embryos and unfrozen. Frozen embryo transfer (FET) has many advantages compared with the fresh embryo transfer procedure and plays an essential role in single embryo transfer (ET) programmes.
Several previous cohort studies have shown similar, or even better perinatal outcomes for singletons, for frozen embryo transfer compared to those from fresh embryo transfer. However, a concern with frozen transfer is whether the cryoprotectants, the freezing or the thawing procedures might have an adverse effect on the embryos and whether, thereby, cryopreservation processes might increase the risk for congenital anomalies.
The authors, Sari Pelkonen et al, state that children born as a result of assisted reproductive technology do have a small increased risk for congenital abnormalities when compared with spontaneously conceived children. However, in assisted reproduction children born after frozen embryo transfer have a similar, low, risk of developing major problems as do children born after fresh embryo transfer. The perinatal outcome in children born after FET is as good as that after fresh ET. The study was focused on singleton births and included 1830 children born after frozen embryo transfer, 2942 children born after fresh embryo transfer and 31 243 children born after spontaneous pregnancies.
The study concludes that perinatal outcomes for 'frozen embryo transfer' children, including the risks for congenital abnormalities, are as good and comparable with the outcomes of other types of assisted reproduction births. This indicates that "... slow freezing is a safe method to use during ART treatments. This is important because of the need for a good and effective cryopreservation programme when implementing the single embryo transfer strategy". The results are reassuring, but it should be remembered that the total number of studied frozen embryo births was limited. When new fertility technologies, including new culture media and freezing techniques, are incorporated into daily practice continuous surveillance programmes will be needed to prove their safety.
Read the article at http://humrep.oxfordjournals.org/content/29/7/1552
More on Planer freezers http://planer.com/products/cryo-freezers.html
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