Background: Despite the widespread use of assisted reproductive technology (ART), few studies analyse its impact on the total fertility rate (TFR). Furthermore, very little is known about how ART affects fertility at older reproductive ages and contributes to family size.

Objective: We aim to quantify the contribution of ART to total and age-specific fertility rates and in relation to the transition to first and subsequent births in Australia.

Methods: Using data from a comprehensive clinical registry of ART treatments, age-specific ART and non-ART fertility rates were calculated and used to decompose the change in the TFR between 2010 and 2017 into ART and non-ART components.

Results: ART represented an increasing and relevant contribution to the TFR, corresponding to an impact of the order of 4% to 5% per annum, or approximately to 1 in 20 births. Increasing fertility rates at age 33 and above exerted a positive effect on the overall TFR, and they were almost entirely attributable to the increasing use of ART. Women resorted to ART especially to have a first child.

Contribution: This is the first study to provide a detailed examination of the contribution of ART to age-specific fertility rates and in relation to parity transition. While most studies focus on the impact of ART on the overall TFR, the importance of ART for the recovery of births at older reproductive ages could be underestimated.