News & Resources

Minimizing the Risk of Multiple Pregnancy

September 11, 2014
By Dr. Randall Loy

The risks of multiple pregnancies are well known and include intense nausea and vomiting, pre-term labor and delivery with the associated risks to the babies (e.g. cerebral palsy), low birth weight, pregnancy-induced high blood pressure, gestational diabetes, increased bleeding risks and cesarean delivery. Despite greater awareness of these and other complications, as well as recent advances in the world of IVF which have improved embryo implantation rates, many patients still insist on a two or three embryo transfer. During the last number of years efforts have been made to define the appropriate number of embryos to transfer in the IVF setting to maximize the chances for a successful single pregnancy while minimizing the risks for twins, triplets and higher order pregnancies. The goal is the single embryo transfer (SET).

Recently published inFertility and Sterility(2014;102:345-347) by Zabeena Pandian and colleagues was a summary of theCochrane Reviewon the number of embryos for transfer in the IVF and ICSI setting.Cochrane Reviews(http://www.cochrane.org/cochrane-reviews) are careful reviews of primary sources of clinical research and are regarded as one of the ultimate standards in evidence-based medical practice. In their review, Dr. Pandian of Aberdeen Maternity Hospital in the United Kingdom, and coauthors considered 14 randomized controlled research studies comparing the number of embryos transferred in 2,165 women. In short, there were no statistically meaningful differences in pregnancy between two SET cycles (either fresh-fresh or fresh-frozen/thawed) compared with one cycle of double embryo transfer (DET). However, as one would anticipate, the multiple pregnancy rate was significantly reduced in the repeated SET group compared with the DET group – approximately 1-3% vs. 14%. There is also no doubt that the single SET cycle is less likely to result in pregnancy than a single DET cycle, approximately 24-33% vs. 45%.

The authors’ conclusion is straightforward: repeated SET may well minimize the various risks of multiple pregnancy in the IVF setting without substantially decreasing the live baby rates. The goal of IVF, now, should be to replace the single best embryo into the best uterine environment. Maybe the title should have beenReady, SET, SET, Go!

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