Hyperemesis gravidarum (severe morning sickness)

Hyperemesis gravidarum is morning sickness to the extreme. If you're among the sufferers, find out what causes it, what the symptoms are, and how it's treated.

woman sitting on the floor next to her bed with feeling ill
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What is hyperemesis gravidarum?

Hyperemesis gravidarum (HG) is an extreme form of morning sickness during pregnancy that causes severe nausea and vomiting in expectant moms. HG affects up to 3% of moms-to-be and causes them to throw up so often that they can't keep down enough food and fluid. This can lead to dehydration, weight loss, and other complications.

Hyperemesis gravidarum symptoms

  • Nausea that won't go away
  • Vomiting multiple times every day
  • Reduced appetite and aversion to foods
  • Weight loss
  • Inability to keep down liquids or solid foods
  • Dehydration (signs include feeling thirsty, urinating less, dark urine, dry mouth or cracked lips, feeling tired or confused, or feeling dizzy or light-headed)
  • Increased salivation
  • Constipation
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Hyperemesis gravidarum causes

Experts are still investigating what causes HG and its milder form – morning sickness. In a 2023 studyOpens a new window, researchers found that women with hyperemesis gravidarum had abnormally high levels of GDF15, a hormone released by the growing fetus. But women who had been exposed to high levels of GDF15 before pregnancy didn't react strongly to it, opening the door for a possible preventative treatment for HG in the future. 

Other factors may also play a role in HG, including rising levels of the human chorionic gonadotropin (hCG) hormone released by the placenta, an increased sensitivity to smells, and a slowed and more sensitive gastrointestinal tract.

You're more likely to have HG if you:

  • Tend to get motion sickness or migraines
  • Are pregnant with multiples
  • Had morning sickness or HG in a previous pregnancy
  • Have a mother or sister who had HG
  • Are pregnant with a girl
  • Suffer from an eating disorder

Hyperemesis gravidarum treatment

  • IV fluids. Your provider will probably give you intravenous (IV) fluids right away, because you'll most likely be seriously dehydrated. Depending on your condition, you may need to be hospitalized for a few days so you can continue getting fluids, vitamins, and medication intravenously.
  • Medication. Many women feel much better after they're rehydrated and are able to control their symptoms with anti-nausea medication. As soon as your condition stabilizes, you should be able to go home and take oral medication.
  • Dietary changes. Your provider may also recommend a diet designed to reduce nausea and vomiting. Both diet changes and medications may be necessary because many women who suffer from HG continue to have some morning sickness well into their pregnancy, even if it's not as severe as before.

In rare cases, you'll need to continue receiving intravenous therapy on and off, either in the hospital or at home.

How HG can affect you and your baby

HG shouldn't affect your baby if you receive appropriate treatment. According to the American College of Obstetricians and Gynecologists (ACOG)Opens a new window, most women with the condition have perfectly healthy babies.

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Studies have shown that severe nausea and vomiting during pregnancy don't result in a higher risk of birth defects or infant mortality. But HG can become a problem if you can't keep down food and liquids, causing you to lose weight. This can result in your baby having a low birth weight.

Although your baby probably won't be affected by hyperemesis gravidarum, the condition is emotionally and physically draining for you. Hyperemesis gravidarum can lead to:

  • Dehydration and an imbalance of electrolytes, which are important for your body to function well
  • Damage to the esophagus and tooth enamel from frequent vomiting
  • Ketosis – a buildup of waste products that results in fatigue, bad breath, and dizziness
  • Thyroid problems
  • Possible liver damage, if your severe nausea and vomiting continues after 16 to 18 weeks of pregnancy
  • Depression

The sooner you're diagnosed with hyperemesis gravidarum, the sooner you can begin treatment and start to feel better.

Do I have normal morning sickness or hyperemesis gravidarum?

The difference between normal morning sickness and HG depends on the severity of your nausea and vomiting, along with other factors, like whether you're gaining a healthy amount of pregnancy weight. Here's a simple comparison:

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 Severity of nausea and vomitingHydrationWeight gain
Morning sicknessBrief episodes of mild nausea that come and go; may vomit once or twice a dayNot dehydratedNormal weight gain despite vomiting
Hyperemesis gravidarumSevere nausea that lasts for several hours a day; vomiting more than three times a dayDehydratedLoss of at least 5 percent of pre-pregnancy weight

Only a healthcare provider can make a diagnosis, so let yours know if you're vomiting constantly and show signs of dehydration or weight loss. They'll start with an exam to rule out other conditions.

Your doctor or midwife will also test your blood to look for electrolyte imbalances and check your urine to see if you're dehydrated or not absorbing enough nutrients. You may have an ultrasound to check on your baby.

When to contact your provider about HG

Contact your provider if you're worried that your nausea and vomiting are something more than morning sickness. Call if:

  • You haven't been able to keep anything (including fluids) down.
  • Your urine is dark and strong-smelling.
  • You haven't been able to pee much in the past 4 to 6 hours.
  • You feel weak, faint, or dizzy.
  • You're vomiting blood.
  • You have a fever.
  • You have abdominal pain.
  • You've lost more than 5 pounds.

If you're newly pregnant and don't yet have an ob-gyn or midwife, and are experiencing symptoms of hyperemesis gravidarum, go to the emergency room (ER).

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If you have ongoing HG, your healthcare provider can give you some guidelines about when to go to the ER for IV fluids. Symptoms that could warrant a trip to the ER include:

  • You haven't been able to keep down any fluids for 12 hours.
  • You've fainted.
  • You can't function normally due to lightheadedness.

More support for hyperemesis gravidarum

Ask your provider or hospital if there are any local support groups for women with hyperemesis gravidarum, or look for online support forums on social media.

You can also visit the Hyperemesis Education and Research Foundation websiteOpens a new window for more information. You'll find research updates, self-care advice for women with HG, and an online forum.

For another place to connect with moms-to-be who have HG, visit the Hyperemesis Sufferers group in the BabyCenter Community.

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Learn more:

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ACOG. 2023. Morning sickness: Nausea and vomiting of pregnancy. American College of Obstetricians and Gynecologists. a new window [Accessed December 2023]

Hinkle SN, et al. 2016. Association of nausea and vomiting during pregnancy with pregnancy loss: A secondary analysis of a randomized clinical trial. JAMA Internal Medicine 176: 1,621-7. a new window [Accessed December 2023]

MedlinePlus. 2023. Hyperemesis gravidarum. a new window [Accessed December 2023]

Merck Manual. 2022. Hyperemesis gravidarum. Consumer version. a new window [Accessed December 2023]

Nature. 2023. GDF15 Linked to Maternal Risk of Nausea and Vomiting During Pregnancy. Opens a new window[Accessed December 2023]

Nature. 2023. Extreme morning sickness? Scientists finally pinpoint a possible cause. a new window [Accessed December 2023]

OWH. 2022. Pregnancy complications. U.S. Office on Women's Health. a new window [Accessed December 2023]

UpToDate. 2023. Treatment and outcome of nausea and vomiting of pregnancy. a new window [Accessed December 2023]

Karisa Ding

Karisa Ding is a freelance health writer and editor with expertise in preconception, pregnancy, and parenting content. A mother of two, Ding finds great joy in supporting new and expectant parents by providing information they need for the life-changing journey ahead. Ding lives in San Francisco with her family.