Number of embryos allowed in fertility treatment should be flexible

Editor—The Royal College of Obstetricians and Gynaecologists' new guidelines for the management of infertility in tertiary care^1–3 are generally welcomed. Guideline 10, however, recommends that the maximum number of embryos should be reduced from three to two for all patients. This is an imprecise way of dealing with a complex problem, eliminating triplets at the expense of some couples having their own child. Regulatory authorities already deprive some women of having their own children because of the decision to fix the upper limit to three in 1987. The college should have evaluated who is at risk of having a multiple pregnancy and made recommendations based on this risk.

A fertility index based on factors associated with the risk of having a multiple pregnancy could be calculated to determine how many embryos to transfer. This should result in women with high reproductive potential receiving one or two embryos and those with low reproductive potential receiving three or even more. We have indirect evidence to support this reasoning. Using gamete intrafallopian transfer, we have transferred more than three eggs to women aged >40 who have a low risk of multiple pregnancy; this technique does not come under the supervision of the Human Fertilisation and Embryology Authority. Our live births/ongoing pregnancies for those aged 41-44 is 15%, compared with about 4.8% from the authority's national data on in vitro fertilisation, and there were no triplets.

We believe that the college's recommendation is flawed. If transferring two rather than three embryos in women aged ⩽40 gives the same chance of a singleton pregnancy there should be a comparable singleton pregnancy rate between centres with different incidences of two embryo transfers. Analysis of data from the Human Fertilisation and Embryology Authority for all ages in 1999 indicates very different rates between our centre (12% two embryo transfer) and centres having a higher incidence—for example, Aberdeen (63%) and Hammersmith Hospital (52%).² The differences were not simply due to an increase in multiple pregnancy—mostly twin pregnancies. The chance of having a birth per embryo transfer for all treatments, including the use of frozen embryos, was greater in our centre (19.5% compared with 14.4% and 12.5% respectively); the chance of a singleton birth was 13.3% compared with 11.1% and 9.9%.

Guideline 10 also states erroneously that there is a significant risk of triplets in women over 40 when three embryos are transferred, but the Human Fertilisation and Embryology Authority's data indicate just one set in 808 transfers. The college should acknowledge that infertile women have different reproductive potentials and risks of multiple pregnancy; it should amend its recommendation to allow for flexibility rather than have patients fit an inappropriate and incorrect medicopolitical dogma.