A heavily pregnant woman and her unborn baby have died after a suspected snake bite in the Mid West WA town of Meekatharra, 775 kilometres north-east of Perth.

St John Ambulance officers were called to a home in Main Street at 8:43pm on Monday.

It was reported the 27-year-old woman had been bitten while outside her home and began fitting.

She alerted family members who called emergency services.

The woman was taken to Meekatharra Hospital but died shortly after arrival.

The ABC understands medical staff at the hospital were unable to save her unborn baby. She was 31 weeks into her pregnancy.

Her body will be taken to Perth for a post-mortem examination, but it could take some months to determine the exact cause of death and type of bite.

Police are preparing a report for the coroner.

Pregnancy may have hastened death

Toxinologist and research fellow at the Australian Venom Research Unit, Dr Timothy Jackson, said the woman's pregnancy may have been a factor in her death, as low blood pressure — or supine hypotension — associated with pregnancy is associated with rapid collapse after a snake bite.

"Some snake bites can have very dramatic effects on blood pressure and some of the very rapid deaths we see in Australia are associated with a syndrome called 'rapid collapse'," he said.

"This is more common after brown snake bites than after bites from other species."

Dr Jackson said rapid collapse was often connected with fatal snake bites in Australia and it could lead to people collapsing within half an hour to an hour of a bite.

Western brown, death adder snakes the prime suspects

Dr Jackson said the deadly western brown snake was the most likely species responsible for the fatal bite.

"In general, they cause over 60 per cent of life threatening envenomings in Western Australia," he said.

The assessment was backed up by experienced reptile enthusiast Corin Desmond, who said the western brown snake was particularly dangerous to vulnerable people.

"The western brown snake is a candidate because they can be quite deadly especially if somebody is already sick, young, old or pregnant.

But he said the desert death adder could also be the culprit

A desert death adder can lash out if surprised. ( Department of Parks and Wildlife )

"If surprised it will strike and they are very deadly," he said.

"Generally the western brown snake is one of the more aggressive than the other venomous snakes you might find out there, certainly a lot more aggressive than the death adder because they're much rarer at the moment, they're scared and they'll try avoid humans.

"The western browns are aggressive and have been known to 'go someone' further.

"Whereas the death adder can have a high mortality rate if there is no anti-venom in time."

Speed, location the key factors in an emergency

Dr Jackson said the treatment window for snake bite varied according to a range of factors, such as the species of snake, amount of venom in a bite, a person's physiological state and when they were bitten.

Remoteness was often one of the biggest dangers for snake bite victims.

"If it takes a long time for people to get to hospital, naturally there is a higher chance things could go wrong for them," he said.

"In remote hospitals they may not have such a big budget for medicine and they may see very few snake bites, not because there aren't many snakes — snakes might be very abundant in those areas — but there aren't a lot of people.

Map Meekatharra is 775 kilometres north-east of Perth

Dr Jackson said the timeframe for treatment was critical.

"Knowing CPR … can be a major factor between life and death," he said.

"With this rapid collapse, we're talking about within an hour of the bite.

"… People in remote communities where they have snakes, it might be a long distance to professional medical care, [so] being first-aid trained and keeping training current is really crucial and can be the difference between life and death."