One in three pregnant women in NSW has her labour induced - a rise of at least 15 per cent in the past 10 years - with almost half of inductions done without a medical reason.
Inducing labour, where women are given drugs such as oxytocin or prostaglandin to stimulate the cervix and start contractions, can increase the chances of a caesarean delivery or cause complications for both mother and baby.
Too many inductions were being performed on pre-term women in hospitals that lacked neonatal respiratory support facilities, despite most premature babies needing help with breathing, researchers found.
Both drugs also make labour more painful because contractions are stronger and longer, leading women to require more analgesia and more time to recover after the birth.
In a study of more than 730,000 births between 1998 and 2007, researchers from the University of Sydney and Royal North Shore Hospital were alarmed to find that half of those having inductions were pregnant with their first baby, a move which could change the way any subsequent births were handled if the induction resulted in a caesarean delivery.
The study, published in the Australian and New Zealand Journal of Obstetrics and Gynaecology, found that one-quarter of women given both oxytocin and prostaglandin had caesareans , compared with 19 per cent of those given prostaglandin alone and 15 per cent who had oxytocin.
The main reasons cited for induction were pregnancies of 41 weeks or longer, hypertension and diabetes, but 45 per cent of women had no medical reason for being induced.
In the past decade the number of inductions carried out on women with hypertension or diabetes rose from 6 per cent to 22 per cent, a result which could be attributed to Australia's the obesity epidemic, an increase in older mothers and better antenatal screening.
The study also found that inductions in private hospitals had increased from 18 per cent to 27 per cent.
But too many inductions were being performed on pre-term women in hospitals that lacked neonatal respiratory support facilities, despite most premature babies needing help with breathing, researchers found.
In another study in the journal, doctors in Queensland, which has the nation's highest caesarean rate, predicted surgical births would soar in the next decade because one-third of women having their first babies were having the procedure.
There was little agreement among doctors on the safety of vaginal births after caesareans and not enough research being done on the subject, they said.