To demonstrate that success rates with in vitro fertilisation (IVF) have been improving despite decreasing the number of embryos transferred.

Materials and Methods
This was a retrospective cohort study comparing live birth outcomes for women who started IVF between 2001 and 2005 with women who started between 2006 and 2010, using life table analysis to allow for the fact that women had differing number of cycles of treatment. The data were obtained from a single IVF centre, Monash IVF Geelong, Victoria. The 2001–2005 cohort consisted of 233 women, and the 2006–2010 cohort consisted of 453 women who started IVF between the specified dates. The main outcome measure was a live birth. Life table analysis was used to estimate the cumulative probability of a live birth after each cycle.

The estimate of cumulative live birth probability demonstrated that the chance of a live birth by cycle five was 75.8% in the 2001–2005 cohort, which significantly increased to 80.1% by cycle five in the 2006–2010 cohort (P = <0.05). There was a mean of 1.8 embryos transferred per embryo transfer in the 2001–2005 cohort, which decreased to a mean of 1.3 embryos transferred per embryo transfer in the 2006–2010 cohort. This was associated with a significant decrease in the multiple birth rate from 24.7% in the 2001–2005 cohort to 7.5% in the 2006–2010 cohort. Conclusion The IVF success rate has significantly improved despite the number of embryos transferred being reduced. This study provides further support for elective single embryo transfers.