In 2010, the Turkish Ministry of Health, in a response to rising rates of multiple births and their attendent complications, passed regulations limiting the number of embryos transferred in an IVF cycle. In women under age 35 in the first 2 cycles, only one embryo can be transferred. In subsequent cycles and in older women, the limit is two embryos
The result in one maternity center, published in this month’s issue of Human Reproduction, was a significant decline in multiple births, NICU admissions and rates of respiratory distress syndrome, necrotizing enterocolitis anemia and pneumonia in newborns, as well as the use of mechanical respiratory support in infants born at that institution.
Lest you worry that pregnancy rates suffered as a result, the authors point out multiple prior studies showing that the adoption of single embryo transfer has not had an adverse impact on pregnancy rates in that country.
This is just one more study adding to the growing consensus that when it comes to fertility treatment, less can be more.
The United States lags behind Europe in adopting single embryo transfer
Single embryo transfer as first line IVF protocol in women under age 35 is increasing worldwide, although the United States is lagging behind European countries in this regard.
According to The American Society for Reproductive Medicine, only about 10% of IVF cycles in the US in 2008 were single embryo transfer, compared with 20% overall in Europe and as high as 60% in Sweden. This is despite randomized trails that show no statistical difference in pregnancy rates with single embryo vs double embryo transfer at the blastocyst stage, and a reduction in twinning from 48% to 0%.
According to ASRM, barriers to adoption of single embryo transfer in the US are both patient and provider-driven, often fueled by financial concerns on both sides. The high cost of IVF cycles in the United States leads patients to attempt to complete their family in one cycle, a strategy that may be penny-wise but pound foolish, as the long term costs resulting from multiple gestation can be much more excessive than that of another IVF cycle. In addition, the manner in which IVF centers are required to report their results encourages multiple embryo transfer. Finally, for single embryo transfer to be successful, IVF centers must be able to select the highest quality of embryo for transfer (not always as easy as it sounds) and have a viable program for freezing unused embryos for future cycles (not all do).
According to the CDC, the rate of twin pregnancies in the United States has risen 76% since 1980, from 1 in 53 to 1 in 31 births. While some of the rise is explained by increasing maternal age (older moms have higher rates of spontaneous twins), the use of assisted reproductive technology accounts for two-thirds of the increase in twinning in the United States.
Although I know of no move afoot to regulate IVF in the United States the way it is in Turkey, the field is moving in the right direction. Not all centers have what it takes to lead to success with single embryo transfer, and not all patients believe they can afford the luxury of multiple IVF cycles to complete their family. Studies have shown that when IVF cycle costs are lower, patients will choose single over multiple embryo transfer.
Who are candidates for single embryo transfer?
Single embryo transfer works best in women under 35 who have more than one good quality embryo resulting from and IVF cycle. It’s also a great option for women undergoing donor egg pregnancy, since egg quality from the donor is expected to be high. Older women and those with poorer quality or number of embryos will still be candidates for higher order transfers. Over time, newer technology that allows selection of the best embryos will only enhance success rates.
