Some hospitals are completely booked for planned caesarean sections on the first two days of next month as pregnant women put off elective cesarians until the new payment kicks in, Sydney's "The Daily Telegraph" newspaper said.
The government announced the baby bonus May 11 as part of a big-spending budget for the next fiscal year, which most commentators agree is designed to win votes at elections due before Christmas.
Mothers who give birth June 30 or earlier get just $700 (US$490).
Prime Minister John Howard was unconvinced his government's policy was affecting the timing of caesarean sections.
"If that were happening, I would be concerned," Howard told reporters Friday. "Whether it's happening, it's very hard to tell."
Doctors concerned about the medical impact of the delays have asked Health Minister Tony Abbott to bring forward the start date of the baby bonus, but the government says there isn't enough time to pass a new bill to change the date before it goes into effect.
Sydney's Royal Prince Alfred obstetrics and gynecology director Andrew Child said the hospital's doctors met this week to plan for extra births in early July.
"They are all a bit concerned that they are getting requests from pregnant mothers to put off the date of birth to July 1," the newspaper quoted Child as saying. "We would always suggest that the baby comes first."
He added, "It is not worth $3,000 to put your baby's whole life at risk."
About 10 percent of pregnant women book a planned caesarean section for a variety of medical and physiological reasons. While doctors give advice, the mother makes the decision on the timing.
Child said the optimum time for a planned caesarean is in the week leading up to the due date, but some women are trying to book 10 days after the due date. The newspaper did not give numbers of mothers who had opted for a late delivery.
"Once they go 10 days past their due date, there starts to be risk to the baby," Child said.