The proportion of babies born through caesarean section globally each year has almost doubled to 21 per cent since 2000, sparking renewed calls for governments to help reverse the "alarming" trend.
In Australia, 33 per cent of about 300,000 babies were delivered through the life-saving surgery in 2014, high above the World Health Organisation's (WHO) recommended rate of 10 to 15 per cent.
New studies published in the latest Lancet show the procedure is being overused in wealthier regions and countries, while it remains out-of-reach in poorer areas.
“Although there is almost universal consensus that c-section use has increased beyond the reasonable level of need in many countries, effective interventions to optimise use have proven elusive," Ana Pilar Betran, a lead author and WHO researcher, said.
One of the studies found C-section use increased from 12 per cent of 16 million births in 2000 to 21 per cent of 29.7 million births in 2015.
In that time, the rate most rapidly increased in South Asia, where it went from 7.2 per cent to 18.1 per cent. But it remained low across sub-Saharan Africa, hovering at 4 per cent.
The rate remained extremely high in Brazil, where in 2009 it hit 50 per cent and has now increased to 56 per cent.
The researchers said in Brazil, particularly high levels of C-sections were seen in women who were highly educated, compared with less educated women.
"C-section use is a health service indicator that has one of the largest disparities between the rich and the poor," they wrote.
"In several countries, the proportion of births by C-section in poor and vulnerable women is close to 0 per cent, implying that some women die because they cannot access life-saving surgery during childbirth."
C-section can improve chances of survival and lower risks of incontinence and prolapse, but experts say there are no benefits in cases where it's not medically necessary.
The second study concluded that the risk of maternal death and disability was higher after a C-section than vaginal birth.
The authors said C-sections had a more complicated recovery and potentially led to scarring of the womb, which has been linked to bleeding, ectopic pregnancy and stillbirth.
They added that emerging evidence showed C-section babies had different hormonal and bacterial exposures during birth, potentially impacting their health.
"Evidence is starting to suggest the lack of exposure to this can make long-term changes to a baby's physiology, particularly around their intestinal, gut microbiome," Professor Caroline Homer from UTS said.
"There appears to be problems, around asthma and obesity, but we need more research."
The third study focused on tackling the overuse of C-section, with the authors identifying key reasons why some women opted for surgery, such as pelvic floor damage and urinary incontinence.
They recommended further research into relaxation training, childbirth training workshops, and meetings to promote supportive relationships with healthcare workers.
In a new position paper published in The Lancet, the International Federation of Gynaecology and Obstetrics called on the medical profession to join forces with governmental bodies and the health insurance industry to reverse the "alarming" trend.
"The delivery fees for physicians for undertaking C-sections and attending vaginal delivery should be the same [and] women should be informed properly on the benefits and risks," it said.
"The situation in very low-income countries requires specific attention, considering that access to C-section is still insufficient in rural areas."
But Professor Hans Peter Dietz, a professor in obstetrics and gynaecology at Sydney Medical School Nepean, did not support the calls, saying governments should not impose targets and shape the conversation between a mother-to-be and her doctor.
"Caesarean sections are going up in countries where affluence is increasing, so it's not surprising that their healthcare is getting better, that doctors have more technical abilities and can do more caesareans and women want a caesarean," he said. "They're all good things."