?Implanting two embryos has been found to actually decrease the chance of a successful pregnancy. Image: Alamy.

Research being presented today at the British Fertility Society annual conference in Edinburgh says that using more than one embryo in IVF can actually decrease the chance of successful pregnancy, according to the Guardian

A study of almost 1,500 embryos who were implanted in women of all ages found that implanting a healthy embryo with one of poorer "quality" dramatically cut the chance of a successful pregnancy compared to just transferring one embryo. Transferring two embryos of good "quality" (as opposed to two of less good "quality") was also no better than one for establishing a pregnancy. If verified, this finding would remove the pragmatic justification for implanting multiple high quality embryos, which are sometimes then selectively "reduced" through abortion. However, it is likely that in practice, multiple embryos will continue to be produced in vitro, some of whom will be discarded and others frozen for possible later use.

"Good" and "poor" embryos

Nick Raine-Fenning, medical director and research lead at Nurture Fertility, said: "The current feeling is that a good embryo will be recognised by the body and will be captured for implantation. But a poor quality embryo should be rejected by your body, your endometrium will reject it. What our research suggests is that if you put a poorer quality embryo back with a good one, it's more likely to compromise the chance of the good one implanting."

Dr Raine-Fenning also said:  "We hope this research will help clinics further reduce the number of multiple births."

Products subject to quality control

Dr Anthony McCarthy of SPUC commented: "The study is revealing in a number of ways. It reminds us that the methods of ovarian stimulation standardly used in IVF are liable to cause high numbers of embryos who may not be healthy.The most badly affected are immediately discarded while others of 'lower quality' may or may not be given a chance of going to term. Human beings produced in this way are therefore treated as 'products' subject to quality control: to be accepted or rejected or 'put on ice' until further notice. Parenthood should always be understood in terms of unconditional acceptance. The cavalier use of human embryos in IVF, including the production of multiple embryos many of whom are discarded, says much about the lack of respect our culture has for the unborn and for parents."