As obesity rates rise in Australia, the administration of epidurals for pregnant women become a concern among anaesthetists.

Losing weight before falling pregnant may save mums-to-be a world of pain during labour.

Research shows that as a woman's body mass index (BMI) increases the likelihood of an epidural failing also increases.

As the prevalence of obesity rises in Australia, the successful administration of an epidural is a growing concern for anaesthetists.

The management of epidurals for obese women is difficult and "can't be swept under the carpet", Dr Victoria Eley, an anaesthetist working at the Royal Brisbane and Women's Hospital, says.

"In trying to provide good anaesthetic care to women, anaesthetists have a lot of concern about techniques and epidurals and anaesthetics that are higher risk for obese women," she told AAP on Monday.

Epidurals involve the injection of a local anaesthetic drug into the epidural space of the spinal cord.

Too much fat around the spine can make it difficult for a doctor to insert an epidural.

"We do know that as the body mass index gets higher that the risk of the epidural being difficult to get in and get into the right place gets more difficult," said Dr Eley.

Also, the ensuing pain relief might not be as effective.

"Because it's difficult to get in, in the first place, it's not exactly in the right spot and if it's not in the right spot the function tends to be poor," she said.

Some in the profession recommend performing an epidural earlier for obese woman.

But there's "not a lot of evidence to support" the practice, creating a dilemma for treating doctors.

"I would suggest that if we actually want some evidence to support early epidural insertions then we need to audit our practice," Dr Eley told physicians at the Australian and New Zealand College of Anaesthetists (ANZCA) conference in Brisbane.

A key factor is a lack of awareness among women of the associated risks of being overweight or obese in pregnancy.

"Many women don't tend to see their obesity as a problem in their pregnancy," Dr Eley said.

While not all women will choose to have an epidural, many do and unless they have consulted with an anaesthetist in the antenatal period they won't be aware it might be harder to achieve.

"Loosing weight has the potential to improve the conception rate, the ability to get pregnant, the health of the pregnancy and the ease and safety in which we can provide anaesthetic care," Dr Eley said.