Implanting two embryos during IVF has been the default technique for certain groups in order to maximise the chances of pregnancy, especially in the past when techniques were less refined, or with clinics or countries which are not so concerned with the problems associated with multiple pregnancies. A recent research programme shows that if one of the embryos is of lower quality than the other it can actually reduce the chances of successful implantation and pregnancy by up to 27%.
Experts have previously believed that the body may focus on the better embryo, but these researchers have now suggested that the body may reject pregnancy altogether based on the quality of the poorer embryo rather than selecting the best candidate.
The research presented at the British Fertility Society annual conference involved data for 1,472 fresh single and double embryo transfers carried out on women across a wide age range. It showed that in addition to reducing chances of pregnancy when the quality of one embryo was well below the other, it also showed that transferring two embryos of good quality was no better than using one. Of course, one should always remember that for every piece of research suggesting one course of action, there is often another suggesting the opposite! That is why it is dangerous for patients to make a decision based on internet research. You should always heed the advice of your doctor and embryologist, each of whom has years of experience weighing up the multitude of factors helping them judge the best course of action for you.
Here at Concept we recommend that patients should have a single embryo transferred to their womb in most cases. We also recommend that, where there are sufficient suitable embryos, they should be cultured in the laboratory to the blastocyst stage, which is usually 2 more days. We no longer charge an extra fee for this, so as to reduce the chances of a patient making a decision for financial reasons. The advantage of blastocysts over 3-day embryos is that, on average, they have a significantly greater probability of resulting in a successful pregnancy, thereby removing one of the arguments for a multiple embryo transfer.
As a result of the recent research, it is to be hoped that more clinicians will recommend to women to only have one embryo put back into their body, especially during the first cycle of IVF. Clinicians and consultants will need to educate patients, who may understandably believe that adding a second embryo will improve chances of success rather than damaging them. They should also remember that the second embryo does not need to be discarded; it can be frozen for use in a second cycle, at a much lower cost, and the cumulative probability of success over two single embryo transfer cycles is usually higher than for a single two-embryo transfer.
However, if the embryos are both of a poorer quality, transferring two may boost the chances of pregnancy. Research increasingly shows that clinicians should focus on quality rather than just the quantity of the embryos when making these decisions.
If guidance is updated following this research, it may also reduce the risk of multiple births which can have an impact on birth risks and long term health of children born via IVF.
While new research helps to set standards, at Concept Fertility we ensure that we have reviewed all possible impacts and work on established guidance to ensure our patients have the best possible chances of success. This approach is how we maintain our results in terms of achieving pregnancies and having them continue to successful births.