What Is Hyperemesis Gravidarum (HG)?

What Is Hyperemesis Gravidarum (HG)?

Hyperemesis gravidarum (HG) is a severe form of morning sickness. While at least 70% of pregnant women may experience the nausea and vomiting of morning sickness, sometimes these symptoms become much more aggravated than is typical—this is hyperemesis gravidarum.

It is estimated that between 0.5% to 2% of pregnant women experience this extreme, persistent form of morning sickness, which by definition is the loss of at least 5% of body weight. Many women with HG are admitted to the hospital for treatment. It's suspected that more women may silently suffer from this condition.

It's unclear how many cases of HG are treated as outpatients or not reported at all due to some pregnant women coping with their symptoms without seeking medical care.

It used to be believed that hyperemesis gravidarum was purely a mental disorder and that the mother was trying to reject the pregnancy for whatever reason. This sexist, dismissive theory has now been debunked. Science has shown that HG is a very real physical condition that can cause serious complications (and physical discomfort) for pregnant women.

Symptoms

For women who experience HG, symptoms tend to progress rapidly beginning around the 6th week of pregnancy. Symptoms usually abate by the 18th to 20th week of pregnancy. However, in as many as 22% of cases, symptoms may last until delivery.

Typical symptoms include:

  • Dehydration (signs of this are dry mouth, persistent thirst, minimal urine output, and/or rapid heart rate)
  • Rapid weight loss
  • Vomiting that causes dizziness or lightheadedness
  • Vomiting three or more times per day

In addition to these, other symptoms can include:

  • Bad taste in the mouth
  • Difficulty reading (from dehydration, which can cause changes to the eye)
  • Increased sensitivity to odors
  • Shivering

Women who experience this condition suffer not only physically but mentally. The stress and strain of being ill and potentially hospitalized have numerous physical and mental effects, including stress, anxiety, and depression.

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What Does Morning Sickness Feel Like?

Diagnosis

Doctors diagnose hyperemesis gravidarum by taking a detailed patient history and doing a physical exam. This might include blood tests to rule out other possible causes for the nausea and vomiting. The doctor likely will check for signs of dehydration, and depending on how far along you are in pregnancy, may check the baby's heart rate. Sometimes a pelvic exam is also done.

Complications

Complications of hyperemesis gravidarum are rare. However, it has been noted that there is an increased incidence of gallbladder problems during and after pregnancy. Retinal hemorrhage and kidney and liver damage can also occur. Your doctor may monitor you for these problems.

Causes

Exactly how and why hyperemesis gravidarum develops is unclear. However, it is believed to be primarily caused by an overproduction of the hormone human chorionic gonadotropin (hCG), which is produced by the placenta. Rapidly increasing blood levels of hCG are seen in women with HG, and the onset of symptoms often parallels that rise.

Some other pregnancy hormones are also believed to be involved in causing HG:

  • Cortisol: This stress hormone rises during HG, but it's unclear if this is a cause of the condition or a result of the stressful nature of experiencing it.
  • Estrogen: Since estrogen can increase your olfactory (smell) sensitivity, it may increase nausea and vomiting.
  • Progesterone: This hormone relaxes smooth muscle, which can delay or halt peristalsis (the wave-like contractions that move food in the digestive tract), which may contribute to the severity of morning sickness symptoms.
  • Prostaglandins: Prostaglandins may suppress cortisol and progesterone, influencing the pattern of HG.

Other contributing factors of HG may include low blood sugar, stress, eating certain foods, and/or motion sickness.

Risk Factors

While it's unclear exactly why some women experience hyperemesis gravidarum and others have mild morning sickness or no nausea or vomiting at all, there are some common risk factors.

Risk factors for developing HG include the following:

  • Being overweight or obese
  • Carrying a girl
  • Carrying multiples
  • Family history of HG (primarily in one's mother and/or sister)
  • First pregnancy
  • Having HG in a previous pregnancy
  • History of motion sickness and/or migraine headaches
  • Trophoblastic disease (abnormal growth of cells inside the uterus)

One retrospective study found that women who had morning sickness severe enough to be hospitalized were slightly more likely to have a girl than a boy: 56% of mothers who were hospitalized with HG in early pregnancy had girls, compared to 44% who had boys. Hospitalization in the later stages of pregnancy did not show this correlation.

Impact on Your Baby

Preterm labor and low birth weight are the two major concerns with babies born to mothers with hyperemesis gravidarum. It is possible that HG may also contribute to electrolyte imbalances. However, with treatment, babies of mothers with HG generally do not suffer ill effects.

As mentioned above, there is also a potential cause for concern for the baby when certain antiemetic medications are used to control the vomiting. This is why they are only used when the symptoms are severe enough to warrant the use of these drugs.

Treatment

HG is treated in multiple ways, depending on the severity of symptoms. Treatment may include the following:

  • Consuming ginger
  • Diet changes
  • Immediate intravenous hydration
  • Medication (use caution as these may have other unwanted side effects), including vitamin B6 and doxylamine (which are available without a prescription) and antiemetic (anti-vomiting) drugs
  • Psychotherapy (there may be mental health components to this condition as well as useful mind-body therapeutic techniques)
  • Acupressure bands or electrical nerve stimulation wristbands
  • Total parenteral (intravenous) nutrition (TPN), a type of feeding that bypasses the gastrointestinal tract
  • Tube feedings

When medications are needed, there are several that can be prescribed. Sometimes, simple antihistamines are used. Vitamin B6 has also shown benefit for women suffering from hyperemesis. There are also herbal and other preparations that have been tried with varying success, like powdered ginger.

The decision to use antiemetic medications can be a difficult one, as some of these drugs are not always risk-free for your baby. When the potential benefits of the medication outweigh the potential risks of the medication to the mother or the baby, as in some cases of hyperemesis, medication may be the appropriate treatment. Discuss with your doctor to find the best treatment protocol for your needs.

Coping

The experience of HG can be particularly challenging emotionally because many women have the belief that pregnancy will be a joyous time in their lives—and this condition is unpleasant to say the least.

Thankfully, most cases of HG will subside by 20 weeks gestation, although, as noted above, some pregnant women still experience this condition at term. Coping primarily involves lifestyle modifications and the various treatments recommended by your doctor. To some degree, you may also need to simply get through it, as well.

Lean on family and friends for as much support (emotional and practical) as possible. This might include running errands, meal preparation, cleaning, childcare for your other children, taking time off work, and/or just being there to talk—or hold your hair back.

Strategies that some pregnant women with hyperemesis gravidarum find helpful include the following:

  • Avoiding a completely empty stomach
  • Avoiding activity right after eating
  • Avoiding foods and smells that trigger nausea
  • Avoiding spicy, fried, sweet, and high-fat foods
  • Choosing bland, low-fat, easy-to-digest foods, like crackers, bread, and bananas
  • Drinking lots of fluids (water is best and ice-cold may go down the easiest)
  • Eating multiple, small, snack-sized meals per day
  • Eating slowly
  • Getting enough rest
  • Placing a cool, damp washcloth on your forehead
  • Showering
  • Using relaxation techniques, such as acupuncture, acupressure, meditation, baths, and deep breathing

A Word From Verywell

Asking for support and compassion from the people in your life (including your doctor or midwife) can help you cope and stay healthy when you have hyperemesis gravidarum during your pregnancy. While the symptoms of HG can be difficult to bear, it can help to remember that there's a big prize waiting for you at the end of this (sometimes nauseating) journey—your baby.

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Article Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. March of Dimes. Morning sickness. Reviewed September 2017.

  2. Fejzo MS, Ingles SA, Wilson M, et al. High prevalence of severe nausea and vomiting of pregnancy and hyperemesis gravidarum among relatives of affected individualsEuropean Journal of Obstetrics & Gynecology and Reproductive Biology. 2008;141(1):13-17. doi:10.1016/j.ejogrb.2008.07.003

  3. National Organization for Rare Disorders. Hyperemesis gravidarum. Updated 2020.

  4. Rashid M, Rashid MH, Malik F, Herath RP. Hyperemesis gravidarum and fetal gender: A retrospective studyJournal of Obstetrics and Gynaecology. 2012;32(5):475-478. doi:10.3109/01443615.2012.666580

Additional Reading
  • Gabbe S, Niebyl J, Simpson JL, et al. Obstetrics: Normal and Problem Pregnancies. Seventh Edition. Elsevier; 2017.