US guidelines restrict number of embryos transferred during IVF

The American Society for Reproductive Medicine (ASRM) and the US Society for Assisted Reproductive Technology (SART) have issued new guidelines limiting embryo transfer during IVF procedures to reduce the occurrence of multiple births. Announced at the annual ASRM meeting, held in New Orleans last week, the revised guidelines recommend that no more than two embryos should be transferred to women under 35 during a single cycle of IVF treatment, and that clinics should consider the possibility of transferring only one. For older women the recommended number of embryos increases, but to no more than five. The guidelines state that for women aged between 35 and 37, up to three embryos should be transferred, with up to four recommended for women aged between 37 and 40, and no more than five for women over 40.

The ASRM indicated that its decision to revise US fertility guidelines came as new medical evidence suggested that high pregnancy rates can still be achieved using fewer embryos in the course of IVF. 'The evidence clearly indicates that we can reduce the number of high order multiple gestations and still maintain high pregnancy rates', said Marc Fitz, chair of the ASRM Practice Committee.

In 1999, ASRM issued guidelines recommending that only two embryos be transferred during IVF to women under 35 with a 'healthy' prognosis. This was updated in 2005 suggesting women under 35 should consider implanting only one embryo. What's new in the latest guidelines is that 'no more than two' embryos should be used by women under 35 and limits are also placed on those over 35, who face reduced chances of success. In 2004, researchers at Harvard Medical School published a report which indicated that the occurrence of multiple births following IVF had dropped dramatically since the original ASRM guidelines were issued. However, latest evidence from the March of Dimes, a US organisation committed to preventing birth defects, infant mortality, and premature birth, suggests that over a third of IVF pregnancies in the US still result in multiple births.

In conjunction with the March of Dimes and the American College of Obstetricians and Gynaecologists, the ASRM issued a report highlighting the need to reduce the risk of premature birth for women undergoing IVF. Around 12.5 per cent of US babies are born prematurely and risk long term health problems. Dr Nancy Green, medical director of March of the Dimes, issued a statement saying that 'limiting the number of transferred embryos will mean fewer higher order multiple gestations, defined as three or more foetuses, and reduce the risk of complications for both the mother and the foetus, including preterm birth'. The organisation suggested additional requirements to the ASRM guidelines, including informed consent documents to make explicit the risk of multiple births, and a publishable annual review of clinics' performance and rates of multiple births. Dr Green has said that 'consumers should demand quality assurance in the fertility business'.

In the UK, the Human Fertilisation and Embryology Authority (HFEA) is currently reviewing its policy after commissioning an expert panel looking into multiple births, which reported last week. The report recommends that for patients under the age of 35, the number of embryos that can be transferred should be reduced from two to one. It also states that sanctions should be taken against clinics that exceed a 'cap' placed on the number of twin births allowed. Clinics which routinely exceed a twin birth rate of 5 to 10 per cent, for example, may be placed under further restrictions regarding the number of embryos they can transfer, or may even face problems renewing their licence.