Worldwide Caesarean section use has nearly doubled in two decades and has reached "epidemic" proportions in some countries, doctors warned Friday, highlighting a huge gap in childbirth care between rich and poor mothers.
They said millions of women each year may be putting themselves and their babies at unnecessary risk by undergoing C-sections at rates "that have virtually nothing to do with evidence-based medicine".
In 2015, the most recent year for which complete data is available, doctors performed 29.7 million C-sections worldwide -- 21 per cent of all births. This was up from 16 million in 2000, or 12 per cent of all births, according to research published in The Lancet.
It is estimated that the operation -- a vital surgical procedure when complications occur during birth -- is necessary 10-15 per cent of the time.
But the research found wildly varying country rates of C-section use, often according to economic status: in at least 15 countries more than 40 per cent births are performed using the practice, often on wealthier women in private facilities.
In Brazil, Egypt and Turkey, more than half of all births are done via C-section.
The Dominican Republic has the highest rate of any nation, with 58.1 per cent of all babies delivered using the procedure.
But in close to a quarter of nations surveyed, C-section use is significantly lower than average.
Authors pointed out that while the procedure is generally over-used in many middle- and high-income settings, women in low-income situations often lack necessarily access to what can be a life-saving procedure.
"We would not expect such differences between countries, between women by socioeconomic status or between provinces/states within countries based on obstetric need," Ties Boerma, professor of public health at the University of Manitoba, Winnipeg, and a lead author on the study, told AFP.
Jane Sandall, professor of social science and women's health at King's College London and a study author, told AFP that there were a variety of reasons women were increasingly opting for surgery.
These include "a lack of midwives to prevent and detect problems, loss of medical skills to confidently and competently attend a vaginal delivery, as well as medico-legal issues."
Doctors are often tempted to organise C-sections to ease the flow of patients through a maternity clinic, and medical professionals are generally less vulnerable to legal action if they choose an operation over a natural birth.
Sandall also said there were often "financial incentives for both doctor and hospital" to perform the procedure.
The study warned that in many settings young doctors were becoming "experts" in C-section while losing confidence in their abilities when it comes to natural birth.
It also identified an emerging gap between wealthy and poorer regions within the same country. In China, C-section rates diverged from 4 per cent to 62 per cent; in India the range was 7-49 per cent.
While the US saw more than a quarter of all births performed by C-section, some states used the procedure more than twice as often as others.
"It is clear that poor countries have low C-section use because access to services is a problem," said Sandall. "In many of those countries, however, richer women who live in urban areas, have access to private facilities have much higher C-section use."
C-sections may be marketed by clinics as the "easy" way to give birth, but they are not without risks.
Maternal death and disability rates are higher after C-section than vaginal birth. The procedure scars the womb, which can lead to bleeding, ectopic pregnancies (where the embryo is stuck in the ovaries), as well as still- and premature future births.
The authors suggested better education, more midwifery-led care and improved labour planning as ways of ensuring C-sections are only performed when medically necessary, as well as ensuring women properly understand the risks involved with the procedure.
"C-section is a type of major surgery, which carries risks that require careful consideration," said Sandall.
In a comment accompanying the study, Gerard Visser of the University Medical Centre in the Netherlands, called the rise in C-sections "alarming."
"The medical profession on its own cannot reverse this trend," he said.
"Joint actions are urgently needed to stop unnecessary C-sections and enable women and families to be confident of receiving the most appropriate care for their circumstances."
They said millions of women each year may be putting themselves and their babies at unnecessary risk by undergoing C-sections at rates 'that have virtually nothing to do with evidence-based medicine.'