The latest report on assisted reproduction from the Australian Institute of Health and Welfare (AIHW) and the Fertility Society of Australia shows that the number of babies born to women who had a single-embryo transfer (SET) is on the rise, and that those babies had better outcomes compared to babies whose mothers had a double-embryo transfer (DET).

The report, Assisted Reproduction Technology in Australia and New Zealand 2005, is the eleventh in the series and shows that SET cycles accounted for 48.3 per cent of embryos transfer cycles in 2005, compared with 28.4 per cent in 2002.

Professor Michael Chapman, clinical adviser of the AIHW National Perinatal Statistics Unit at the University of New South Wales said that since 2002 when the Fertility Society of Australia recommended single embryo transfer in women under 35 years of age and never more than a two embryo transfer in any women, there has been a significant increase in the number of single-embryo transfers and so a reduction in twin pregnancies with their associated increased mortality and brain damage.

'In 2005, 86.0 per cent of deliveries following embryo transfer cycles were singleton deliveries, the highest proportion ever reported,' Professor Chapman said.

'Only 8 per cent of SET live-born babies were low birth-weight, compared to 25 per cent of DET live-born babies. These SET babies had a mean birth-weight of 3,302 grams, which is markedly higher than the average birth-weight of 2,937 grams of DET live-born babies,' he said.

For singletons born as the result of a SET, the proportion of preterm birth was 9.6 per cent but rose to 11 per cent for singletons born as the result of a DET.

Similarly, low birth-weight was reported for 5.8 per cent of SET live-born singletons but 7.9 per cent of DET live-born singletons.

The perinatal death rate was also lower in SET singletons (7.3 deaths per 1,000 births) than in DET singletons (12.2 deaths per 1,000 births).

In Australia and New Zealand in 2005, there were 51,017 treatment cycles, including 3,356 donor sperm insemination cycles. Of these cycles, 91.1 per cent (46,481) were from Australian fertility centres and 8.9 per cent (4,536) were from New Zealand's centres. Not surprisingly the number of babies born after IVF treatments has reached an all time high, accounting for almost 3 per cent of births in Australia.

Of the 9,764 babies born to women who had treatment in Australia and New Zealand in 2005 75.6 per cent (7,381) were singletons, 23.5 per cent (2,298) were twins, and 0.9 per cent (85) were higher order multiples.