Single embryo advice to IVF clinics will reduce the number of multiple births

Experts in the UK are advising that wherever possible, only one embryo per IVF cycle should be transferred in order to cut the rate of multiple births.

The British Fertility Society (BFS) and Association of Clinical Embryologists says multiple pregnancies pose a higher health risk to both mother and babies and transferring only one embryo to those women most at risk of having twins is the only effective method to reduce the multiple birth rate after IVF treatment.

The Human Fertilisation and Embryology Authority (HFEA) has asked clinics to cut the multiple pregnancy rate from an average 24% to 10% in three years.

Currently, many clinics choose to transfer two embryos into a patient's womb during IVF treatment in order to maximise the chance of a successful pregnancy but this also raises the risk of a multiple pregnancy.

Multiple pregnancies are associated with a raised risk of miscarriage, stillbirth, premature birth, low birth weight and long-term developmental problems and mothers too have an increased risk of the potentially life-threatening pregnancy condition pre-eclampsia, as well as diabetes and heart disease.

The new guidelines are published in the journal Human Fertility, and offer advice on how clinics can adopt a single embryo transfer policy, including careful assessment of patients' suitability.

Most multiple IVF pregnancies occur in women under the age of 37 and it is this group which the guidelines suggest is suitable for single embryo transfer, on the proviso that spare high quality embryos are available to be frozen for possible later use as this avoids the need for women to undergo further costly cycles of ovary stimulation to harvest more eggs.

Clinics are also being urged to provide more "mild" IVF cycles which involve collecting fewer eggs and creating fewer embryos, as three mild cycles are said to be as effective as two more vigorous cycles, with fewer complications.

BFS says the success of the new strategy will depend on more NHS funding and elective single embryo transfer must be made the norm for women in the UK, as it is elsewhere in Europe.

The National Institute for Health and Clinical Excellence (NICE) recommends patients should be entitled to up to three free IVF cycles on the NHS.

Since the world's first test-tube baby, Louise Brown, was born in 1978, more than 3.5 million babies have been born worldwide using assisted reproductive technology.

Because more women are waiting longer to have children, the demand for IVF has risen significantly; most treatments are for women aged between 30 and 39 and the technique involves surgically removing eggs from a woman's ovaries and combining them with sperm in the lab - doctors then pick the best embryos, usually one or two, and implant them in the woman's uterus.

Some European governments have already mandated single embryo transfers to reduce multiple pregnancies.

Annual figures from the HFEA for Britain show that of 11,262 children born through IVF treatment, 4,000 were twins.