An international study has suggested elective single-embryo transfer (eSET) during IVF may improve chances of delivering a healthy baby compared to double-embryo transfer (DET), although women receiving DET are more likely to become pregnant in the first place.
The team led by researchers from the University of Aberdeen collected data from 1,367 women in previous trials who had undergone IVF - 683 by eSET and 684 by DET. The findings showed that the chances of a full-term single birth (over 37 weeks) following eSET were almost five-times higher than those following DET.
It also found eSET to reduce the risk of premature births, with pregnant women being 87 percent (%) more likely to avoid a premature birth before 37 weeks as a result of the implantation method. Furthermore, the likelihood of having a baby of low birth weight after eSET was one third of the chance following DET.
Even though the pregnancy rate following eSET was lower - 27% of women undergoing IVF after eSET delivered a healthy baby, compared with 42% after DET - the difference was reduced upon implantation of a further frozen single embryo after the initial transfer, giving an increased success rate of 38%. The researchers concluded that given the findings of the study, eSET should become the 'default position' in IVF.
Despite increasing success in infertility treatments over recent years, concerns have been growing regarding rising multiple pregnancy rates, which are associated with increased maternal and perinatal illness and death, as well as increased costs to the health service. Experts believe that by transferring fewer embryos during IVF the risk of multiple births can be reduced.
The findings are welcomed by the Human Fertilisation and Embryology Authority (HFEA), whose policy of reducing multiple births through minimising DET saw cases fall from 24% to 20% between 2008 and 2009. The HFEA's aim is to reduce rates further still to 15% by March 2012.
Professor Allan Templeton, Chair in Obstetrics and Gynaecology at the University of Aberdeen, explains: 'At a time when the beginning of assisted reproduction is being recognised as an outstanding contribution to medical science, practitioners have a responsibility to develop its use wisely'.
'Doctors managing infertile couples are no longer entitled to take risks with the health of the next generation', he said.
The study was published in the British Medical Journal.