Whether it's 12 weeks of feeling vaguely carsick or vomiting so severe that you end up in hospital, if you've experienced a pregnancy, you're probably familiar with morning sickness.

It's a cruel term, because those who've experienced it know that it doesn't constrain itself to the mornings, so experts prefer to call it nausea and vomiting of pregnancy, said obstetric physician Sandra Lowe.

But despite the fact that some level of nausea and vomiting in pregnancy is very normal, it's still not well understood, even by health professionals, Dr Lowe said.

"There's a real absence of understanding of this condition amongst doctors, midwives, pharmacists, GPs, family members," she said.

"There are still a lot of people who are told it's in their head — which is completely incorrect."

Dr Lowe and her colleagues are aiming to correct this lack of understanding with new guidelines for the treatment of nausea and vomiting during pregnancy, announced at the recent Royal Australian and New Zealand College of Obstetricians and Gynaecologist annual scientific meeting in Melbourne.

She said the lack of understanding about pregnancy nausea was especially problematic for women at the more extreme end of the spectrum: those with hyperemesis gravidarum.

"For the vast majority of women it's a mild problem, they can manage it with lifestyle changes, but for a small proportion it's a really serious disease," Dr Lowe said.

"It's also associated, in the worst cases, with adverse pregnancy outcomes."

Tips for managing vomiting and nausea in pregnancy

For most women, lifestyle changes are enough to keep nausea to a manageable level, Dr Lowe said.

Reconsider your multivitamin: "Those large pills that people take as multivitamins are often going to be making them sick if they're already got nausea and vomiting," Dr Lowe said. She recommended substituting the essential vitamins, folic acid and iodine, which can be taken in smaller tablets that are less likely to make you sick.

"Those large pills that people take as multivitamins are often going to be making them sick if they're already got nausea and vomiting," Dr Lowe said. She recommended substituting the essential vitamins, folic acid and iodine, which can be taken in smaller tablets that are less likely to make you sick. Rest when you can: Nausea often hits when you're fatigued, so heading it off at the pass by resting can help.

Nausea often hits when you're fatigued, so heading it off at the pass by resting can help. Avoid strong smells: When you're already feeling queasy, strong smells can make it worse. If possible, change your commute so you aren't stuck on smelly buses or trains, and see if you can delegate food preparation and childcare tasks like changing nappies.

When you're already feeling queasy, strong smells can make it worse. If possible, change your commute so you aren't stuck on smelly buses or trains, and see if you can delegate food preparation and childcare tasks like changing nappies. Vitamin B6 and ginger: There's evidence that both of these over-the-counter supplements can help manage nausea and vomiting, according to Dr Lowe.

There's evidence that both of these over-the-counter supplements can help manage nausea and vomiting, according to Dr Lowe. Eat and drink what you can, when you can: "It doesn't matter if they have their big meal at lunchtime and don't eat anything in the evening, if that's what works for them."

"It doesn't matter if they have their big meal at lunchtime and don't eat anything in the evening, if that's what works for them." Don't be afraid to ask for help.

Dr Lowe acknowledged part of the struggle for many women was that nausea and vomiting is often most severe in the first trimester of pregnancy, before people might be ready to let others know they're expecting.

"One of the problems is they've often not told people that they're pregnant yet," she said.

"They can't tell work why they want to work from home. They can't explain to their mother-in-law why they want them to take the kids.

"So one thing I would suggest is encouraging them to share their pregnancy early. There's no shame if anything happens — people get concerned they're going to miscarry."

What about severe nausea and vomiting?

While most women's experience with pregnancy nausea and vomiting is unpleasant but manageable, for a small proportion of women it becomes severe enough to threaten their health, or that of their baby.

Clinicians call this hyperemesis gravidarum. This new guideline clearly defines hyperemesis gravidarum as nausea and vomiting so severe it causes dehydration, electrolyte abnormalities and weight loss of 5 per cent of pre-pregnancy weight.

The Duchess of Cambridge famously suffered from hyperemesis gravidarum. ( Supplied: Kensington Royal )

"[Mothers] can have major complications, they vomit so much that they bleed from their gut. They can get such major vitamin deficiencies that it affects their brain function," Dr Lowe said.

"They're more likely to get small babies, they're more likely to get pre-term babies."

There are medications that can help control hyperemesis gravidarum, but Dr Lowe said women and doctors alike were often wary of using them.

This is in part due to fear around the birth defects caused by thalidomide, a drug used in the late 1950s and early 60s to treat pregnancy nausea.

"People are frightened to use drugs. The doctors are frightened, the women are sceptical or concerned. So it's extremely important that doctors are confident to explain how modern drugs can really help without significant risks to the growing baby," Dr Lowe said.

"Some women do need medication. So this guideline very expertly outlines the benefits, the risks, the alternatives, the options for women in 2019."

She hoped the new guidelines would help doctors treat women before their nausea and vomiting becomes severe, and empower women to make informed decisions on how to manage their symptoms.

"We have no bandwagon to push for pharma. We are certainly not trying to create a disease from something that's normal — but we're trying to help that really small group of women who are beyond having just a bit of morning sickness."

Your morning sickness stories

I lost 5 or 6 kg in my first trimester. Chose food by what was least disgusting on the way up and the winner was pineapple mint frappe.

— Alison

"Had awful [morning sickness] with my first pregnancy. Definitely triggered by certain smells — especially strong soaps and shampoos, which I now have a 'nausea bodily memory' of and still find hard to smell 10 years later. Ugh. It was so constant it actually felt quite lonely."

— Anna

Lisa went as far as shaving her head because strong smells triggered her nausea:

"Sense of smell was hectic so hated washing my hair because of the too-strong shampoo smell and couldn't stand the smell of dirty hair."

"I generally feel like I've gotten car sick even when I'm just sitting down. And once I vomited so hard that I peed myself on the side of the Pacific Motorway."

— Raimey

It was awful. It took me a long time to eat salt and vinegar chips and drink ginger ale again.

— Rebecca

Samantha needed ice to keep the nausea at bay:

"The thing I most consistently ate through both pregnancies was ice though. I couldn't freeze it fast enough, so I'd buy at least 2 bags of ice a week! I had a brand preference also because the pieces were the right size and it tasted better!"