Study shows benefits of one embryo in IVF plan

Published on Tuesday 21 December 2010 18:07

WOMEN who have only one embryo transferred during IVF are almost five times more likely to deliver a baby at full term than those having two embryos put back, according to new research.

Babies are also far more likely to be born a healthy weight if they are the result of a single rather than multiple pregnancy, a review of studies found.

Fertility clinics across the UK are coming under increasing pressure to drive down the number of multiple pregnancies resulting from IVF.

Critics say the poor provision of IVF on the NHS - despite guidance saying women should get three free cycles - means some couples feel desperate to have two embryos put back.

Twin and triplet pregnancies are linked to a higher chance of premature delivery, low birth weight and miscarriage. These risks have not consistently been shown to be higher for IVF twins than those conceived naturally.

The latest study, published in the British Medical Journal (BMJ), involved 683 women having a single embryo transfer and 684 having a double transfer.

Overall, the live birth rate using a single fresh embryo was lower than when two fresh embryos were transferred.

However, those women who had one fresh embryo transferred and then a second using a frozen embryo had similar success rates overall.

The odds of a baby being born at term (over 37 weeks) after single transfer was five times higher than for a double transfer.

Pregnant women were 87 per cent more likely to avoid a premature birth before 37 weeks with the single embryo.

The authors, led by a team at Aberdeen University, concluded: "Elective single embryo transfer results in a higher chance of delivering a term singleton live birth compared with double embryo transfer.

"Although this strategy yields a lower pregnancy rate than a double embryo transfer in a fresh IVF cycle, this difference is almost completely overcome by an additional frozen single embryo transfer cycle."