Women who have one embryo transferred during IVF treatment are five times more likely to give birth to a healthy baby than those who receive two embryos, research shows today.
Those who have two embryos are more likely to get pregnant but are at greater risk of delivering a premature or low-weight child, researchers found.
The findings, in the British Medical Journal, will increase the pressure for double embryo transfer (DET), which is already discouraged, to be ended because it risks pregnancies involving twins or triplets. UK fertility clinics should halt the practice as multiple pregnancies put mother and child at risk, the researchers say.
Twin and triplet pregnancies are associated with a higher risk of miscarriage, as well as prematurity and low birthweight. But some fertility experts say the widespread lack of IVF treatment on the NHS, which is meant to offer three free cycles to all, means some women seek two embryos.
An international research team, led by Aberdeen University scientists, studied data on 1,367 women who had taken part in eight previous trials who had either had elective single embryo transfer (eSET) or DET.
A full-term birth, at least 37 weeks, after eSET was nearly five times more likely than with DET, they found. Women were 87% more likely to avoid a premature birth after eSET, while their chance of having a low-weight baby was only a third of those who had DET.
The researchers say "elective single embryo transfer should be the default position" for all the 35,000 women who undergo IVF in the UK every year.
The Human Fertilisation and Embryology Authority welcomed the study. Its policy of minimising DET use has helped see multiple pregnancy rates after IVF drop from 24% in 2008 to 20% last year. The regulator hopes to reduce that still further, to 15%, by the end of March 2012.
Article: 23rd December 2010 www.guardian.co.uk
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