Jetstar has started charging passengers to travel with babies on their laps during domestic and international flights.
Passengers on the budget airline will pay $30 per one-way journey to carry a child up to two years old on their lap on domestic Australian flights and $50 on international flights.
The charges came into effect on Monday. It was previously free to bring infants on domestic flights and on flights between Australia and New Zealand. Other international flights previously had a $40 fee.
A Jetstar spokeswoman said introducing the charges brought Jetstar into line with its low-cost competitor Tigerair.
"We know that fees and charges can be unpopular, but giving customers' choice and charging each customer for what they actually need helps us to offer the lowest possible fares, every day," she said.
Qantas, Virgin Australia and Air New Zealand charge passengers an extra 10 per cent on top of their full fare to carry a baby on international flights. It is free to bring a baby on Qantas and Virgin domestic services.
Jetstar's infant fee includes an allowance for up to four oversized infant items, such as prams or strollers.
Babies older than two years old must have their own seat.