Culturing embryos to the blastocyst stage during in vitro fertilisation (IVF) increases the likelihood of pregnancy in patients for whom standard IVF has failed, according to a paper published in the August issue of Fertility and Sterility.
Dr Jose R Cruz and colleagues at The George Washington Medical Center in Washington DC retrospectively compared the pregnancy rates of 22 IVF patients who underwent standard embryo transfer on day 3, with that of 15 patients who underwent blastocyst transfer on the fifth or sixth day of development. Each woman had experienced at least three IVF failures.
The authors report that 40 per cent of women in the blastocyst group achieved pregnancy compared with 9.1 per cent of those undergoing embryo transfer. The authors add that fewer blastocysts needed to be transferred to achieve pregnancy, thereby reducing the chance of multiple pregnancy.
A separate paper published in the same issue of Fertility and Sterility retrospectively reviewed the records of 29 IVF patients who had two blastocysts transferred and 24 patients who had three transferred. The viable pregnancy rates were statistically similar in both groups but two-blastocyst transfer eliminated the risk of triplets while maintaining the same high success rates of transferring three blastocysts, concludes Dr Mikli and colleagues at Stanford University in California.