Multiple births after in vitro fertilisation (IVF) are increasing in number and carry with them undeniable risks to the mother and particularly to children born as multiples. This, coupled with the pressure on children's services brought about by the rising number of premature twins and the increasing success rates of SET, means that SET can confidently be recommended to appropriate patients. (See Why should I recommend SET?)
International evidence, suggests that correctly targeted eSET, when coupled with frozen follow-up treatment, should not substantially reduce birth rates. However, for patients whose initial treatment with a fresh embryo is unsuccessful, treatment with further frozen embryos will take longer and may involve some additional cost, depending on the policy of their Primary Care Trust (PCT).
If success is measured on a narrow, per-transfer basis, then this may give a misleading view of success rates. However, if a treatment cycle includes treatment with both fresh and frozen embryos, evidence from other countries where this policy has been adopted more widely shows that pregnancy rates are maintained.
The HFEA is currently carrying out a review of how clinics' performance is presented in the Find a clinic tables, and whether this is an obstacle to clinics tackling their multiple birth rates. This is part of a broader consultation, scheduled for autumn 2008.
The Association of Clinical Embryologists (ACE) has proposed grading schemes for early cleavage stage and blastocyst embryos. A national External Quality Assurance (EQA) scheme is also being developed. These schemes may help to standardise and improve grading systems. Further research is still required to identify the embryos with the highest implantation potential. Several methods, including metabolomic profiling may also be beneficial in future.
Although any decision ultimately rests with the individual clinician, guidance has been issued by the British Fertility Society and Association of Clinical Embryologists. These guidelines can be found on the website of the journal Human Fertility.
Despite the HFEA Code of Practice guidelines, the multiple birth rate is still too high. To address this problem, the HFEA carried out an extensive review and consultation process, culminating in an outcomes-based policy.
The Infertility Newtowk UK have published a factsheet explaining why and how fertility clinics should be advising their patients to have a single embryo transfer (SET).
Download the factsheet (305 KB)