The guidelines for IVF treatment need to be revised to improve access for obese women, a professor in reproductive medicine says.

Key points: Doctors are advised not to provide obese women with IVF because of numerous risks for the mother and baby

Doctors are advised not to provide obese women with IVF because of numerous risks for the mother and baby Professor Kelton Tremellen says the blanket cut-off for patients who have a BMI over 35 needs to go

Professor Kelton Tremellen says the blanket cut-off for patients who have a BMI over 35 needs to go He says while doctors strive to do no harm, doing nothing can also cause a lot of stress

Kelton Tremellen, from Flinders University, is also a fellow of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

The college advises doctors not to provide obese women with IVF or any form of assisted reproduction.

"If I were to follow the college's view, then we'd be turning away a lot of patients and that would create a significant amount of stress," Professor Tremellen said.

He has released a paper calling for a revision of the treatment guidelines, saying the ban is unwarranted.

"What I'd like is a more refined view on this, that we don't just have a blanket cut-off for patients who have a BMI (body mass index) over 35, where we say we're not treating you," he said.

"We should instead look at how healthy they are — other co-morbidities like high blood pressure, diabetes and such that pose extra risks to the patient — and how successful have they been in the past at losing weight," he said.

In his paper released today, Professor Tremellen said the guidelines for doctors were unjust to women, even though they were designed to help them.

"We're brought up as doctors to first do no harm. Some doctors are concerned that if they give a patient treatment and a harm were to come to them, they've done an evil," he said.

"But they need to recognise that there's harm in doing nothing. Women who are unable to have children, there's a much higher risk of depression and anxiety and a doubling in the suicide rate. So doing nothing is not necessarily doing the best thing."

The guidelines, he claims, can be classified as discrimination.

"Especially when you consider the low socio-economic group," he said.

"The Indigenous patients have a lot higher incidents of obesity than the general population, so you're almost discriminating against those two disadvantaged groups in this particular policy.

"Obviously that wasn't the original intent, but that is a potential end product of that."

Obese women face risks when falling pregnant

For a woman who is overweight or obese, falling pregnant is more difficult than those who are in a healthy weight-range.

"We do know that as a woman gets more obese, the quality of her eggs declines and also probably more importantly the uterus becomes hostile towards that embryo and that probably accounts for why there's a higher miscarriage rate as well," Professor Tremellen said.

The risk of pre-eclampsia, which causes circulation problems, triples in obese women.

It can be hard to reach eggs in the ovaries of obese women for IVF treatment. ( ABC News )

And the risk of pregnancy-related diabetes is eight times more in obese women than those in a healthy weight range.

Another issue is safety during egg retrieval for IVF.

When a woman is overweight, her ovaries are pushed up high away from the top of the vagina by extra fatty tissue in the pelvis.

This can cause problems in IVF because a needle is pushed in to reach the eggs in the ovaries. If the ovaries are too high, it is unsafe to use the needle to get the eggs out.

'I'm really grateful ... otherwise I wouldn't have had my baby'

Paula Fahey was classified as obese when she fell pregnant at 31, but she was offered IVF by her specialist.

"I was very fortunate. My specialist gave me as much access as I wanted for IVF treatment. I was never turned away based on my BMI or my weight," she said.

"I know of other people who have gone through IVF who have been told they can't access it because of their weight, but I was never met with that, which I'm really grateful for. Otherwise, I wouldn't have had my baby."

Ms Fahey went through 28 rounds of IVF — there were 14 egg retrievals and the rest were frozen embryo transfers.

"It was really hard work and quite emotional having a lot of disappointment through that time, but we just kept persisting," she said.

"I had a great pregnancy — I didn't have any diabetes, I didn't have any blood pressure issues. I was really healthy and just enjoyed it, which was great.

"I just think they [doctors] need to really view each case individually and not just look at BMI for patients with IVF."

Medical director of IVF Australia, Peter Illingworth, agreed the guidelines needed to be revised to allow obese women access to fertility treatments.

"I think there has been a problem in the past with women with serious weight problems being fat shamed," he said.

"There is no doubt that women who are overweight face a series of risks and problems, both for themselves and their children.

"There is no doubt that it's very important for women who have a weight problem to do whatever they can to reduce that weight before they try to conceive. The health risks of being overweight are undoubted.

"However, on the other hand, there are many women who struggle to lose weight, and despite surgery and despite very intense efforts to try and manage their weight, find themselves unable to do so.

"I think that the central point made of this paper is a very valid one: that women should not be denied access to fertility treatments simply because they have a weight problem."