Background
The number of twins born in Australia steadily increased from 2420 sets in 1983 to 4458 sets in 2010. At one stage, almost 25% of all twin deliveries in Australia were a consequence of assisted reproductive technologies.

Aims
To determine the influence of a policy of single embryo transfer (SET) on the rate of multiple deliveries in Australia.

Methods
We used population data to compare the prevalence of twin and higher order multiple births in women giving birth in Australia before and after the implementation of the RTAC COP 2001 and 2005 revisions for ART units.

Results
There was a steady fall in the twin delivery rate for assisted reproductive technologies from 210.4 per 1000 deliveries in 2001 to 84.3 per 1000 deliveries in 2009. In 2009, assisted reproductive technologies accounted for approximately 16% of all twin births from 3% of all conceptions, substantially less than the 24.5% in 2002.

Conclusions
The decline in multiple births is multifactorial. However, the fall in the proportion of ART multiple births has paralleled adoption of a voluntary policy of SET within a setting of largely public funding of ART.