IVF: why one egg is better than two

Women who have one embryo transferred via IVF instead of two have a higher chance of taking home a baby and face lower risks, new research has found.

A study on the outcome of IVF treatment for 406 women under the age of 38, conducted by an Australian IVF clinic, found that two-thirds of women took home babies regardless of whether they had one egg transferred or two.

But of the group who had two eggs transferred, there was a twin pregnancy rate of 34 per cent, compared with 7 per cent in the single-embryo transfer group. In the group that had two eggs transferred, five babies died from premature delivery, the study, published in the journal Fertility and Sterility, also found.

Mark Bowman, clinical director of Sydney IVF, said there had been an increasing trend towards single-egg transfer and this study confirmed it was the safest and most effective option for women under 38.

"With single-egg transfer, people still have the same chance of having a baby but without exposing themselves to the significant risk of twins," Dr Bowman said.

Melbourne IVF chairman John McBain said more couples were now opting for a single-embryo transfer. He estimated that five years ago, Melbourne IVF performed twice as many two-embryo transfers as single-embryo transfers. Now, about four single-embryo transfers were performed for every three transfers of two embryos.

Monash IVF medical director Gab Kovacs said couples should be able to choose to transfer one or two embryos. He said more were opting for single-embryo transfer, and "as a matter of principle we should certainly look more seriously at putting just one back instead of two".

Professor Kovacs said that in 2005, about half the transfers at Monash IVF were single-embryo.