Obesity is contributing to the growing rate of caesarean section births in New Zealand.
Almost a quarter of New Zealand women give birth by caesarean section and experts believe rising levels of obesity are contributing to the statistic.
New Zealand College of Midwives midwifery adviser Lesley Dixon said with 28 per cent of the population now obese, it had an impact on pregnancy.
"Women who are morbidly obese, having a Body Mass Index of 35 or 40 and over, generally those women would have higher risks of caesarean sections," Dr Dixon said.
In 2011 a New Zealand study found obese pregnant women were at increased risk of complications including caesarean section and pre-eclampsia.
Other complications include gestational diabetes, induction, larger babies, post-partum haemorrhage and stillbirths.
The Scope study of more than 3000 New Zealand and Australian pregnant women found 25 per cent of overweight women and 36 per cent of obese women who went into labour at full-term delivered by caesarean, compared to 18 per cent of women with a normal body weight.
The findings by Royal Australian and New Zealand College of Obstetricians and Gynaecologists Fellow Professor Lesley McCowan were backed up by a three-year UK-wide national survey which showed only 55 per cent of women with a BMI greater than 35 gave birth naturally, and that caesarean delivery in larger women was associated with higher risks and increased health care costs.
The New Zealand College of Midwives was so concerned by the issue that Dr Dixon has co-written an article for the Midwifery News aimed at advising midwives on how to manage obese clients.
"If we've got increasing numbers of women with obesity during pregnancy we need to consider what are the risks for those women and how do we work with these women during their pregnancy."
A 2008 Australian and New Zealand Journal of Obstetrics and Gynaecology article on obesity in pregnancy said there were two possible explanations for caesarean intervention.
One was complications. The other was that the increased amount of soft tissue in the maternal pelvis triggered a failure to deliver naturally, necessitating a caesarean.
However Auckland Obstetric Centre obstetrician Dr Martin Sowter said it was "absolutely not the case" that New Zealand women were "too pudgy to push".
"It's much too simplistic to say people are too pudgy to push."
Dr Sowter said while obesity was a personal issue, the social deprivation and exclusion that led to it was a societal issue associated with poverty and poor access to health.
He said the number of caesarean sections at National Women's Hospital had remained the same at about 33 per cent, since 2006. "But it's higher than it was 15 years ago."
Almost one third of pregnant patients at the hospital were overweight, with 15 per cent obese, he said.
He did not think New Zealand's rate of caesarean section was excessively high.
Dr Dixon said most women did not "choose" to have a caesarean. Instead they might have to elect one if complications arose during pregnancy.