The proportion of deliveries as a result of Assisted Reproduction Technology (ART) in which one baby was born has risen, reflecting a decrease in the number of embryos transferred per ART treatment cycle, according to a report released today by the Australian Institute of Health and Welfare (AIHW).
The report, Assisted reproduction technology in Australia and New Zealand 2004, shows that during 2004, 41,904 ART treatment cycles were undertaken in Australia and New Zealand, 8,794 cycles resulted in a pregnancy and 6,792 resulted in a live delivery.
'Of all deliveries resulting from ART treatment in 2004, 82.8% were single gestation deliveries compared with 80.0% in 2002,' notes Professor Michael Chapman, spokesman for the AIHW's National Perinatal Statistics Unit (located at the University of New South Wales), 'and this increase reflects a change in the number of embryos transferred per cycle.'
'In 2004, 40.5% of cycles with embryo transfer involved the transfer of one embryo and 56.3% involved the transfer of two embryos. In 2002, these proportions were 28.4% and 65.6% respectively' comments Professor Chapman.
For ART treatment cycles where women used their own embryos, 73.4% of women who had a cycle in which a single embryo was transferred were aged less than 38 years.
In 2004, the delivery of at least one live baby was achieved in 22.8% of transfer cycles where women used their own fresh embryos, while the figure for women who used their own thawed embryos was 15.6%.
'When we look at women who used their own fresh eggs, women aged 25-29 years achieved more successful outcomes, with 34.7% of transfer cycles achieving a live delivery, while women aged 40 years and over had a success rate of 7.8%,' says Professor Chapman.
Of the 8,038 babies born to women who had ART treatment in 2004, 71.4% were singletons. About one-quarter of babies were born preterm (less than 37weeks gestation) and 10.9% of singletons were born preterm.
One fifth of live births to women who had ART treatment in 2004 were classified as being low birthweight (less than 2,500g). Of live born singletons, 7.5% were classified as low birthweight.