What Is Hg In Pregnancy? Symptoms And Treatment

Hyperemesis gravidarum (HG) is a severe form of nausea and vomiting during pregnancy that goes far beyond typical morning sickness. It causes persistent, extreme vomiting that can lead to dehydration, weight loss, and electrolyte imbalances requiring medical treatment. HG is not a psychological condition or something a woman can “snap out of”—it is a medical complication of pregnancy that affects about 0.3% to 3% of pregnancies.

How Is HG Different From Regular Morning Sickness?

Morning sickness is common and uncomfortable. It usually involves mild to moderate nausea that may or may not include vomiting. It typically improves by the second trimester, around weeks 12 to 14.

HG is different in both severity and duration. Women with HG often vomit multiple times per day, cannot keep down food or fluids, and lose weight. The condition can last well beyond the first trimester. Some women experience symptoms for the entire pregnancy.

The key difference is the physical toll. Morning sickness generally does not interfere with hydration or nutrition. HG does. If a pregnant woman cannot keep fluids down for more than 12 hours, that is a medical concern that requires evaluation.

What Causes Hyperemesis Gravidarum?

The exact cause is not fully understood, but the evidence points strongly to hormones. Human chorionic gonadotropin (hCG) rises rapidly in early pregnancy and peaks around the same time HG symptoms typically begin. Some research suggests the severity of symptoms tracks with hCG levels.

Estrogen also rises sharply in the first trimester. Some studies indicate that women with higher estrogen levels during pregnancy have a higher risk of severe nausea and vomiting.

There appears to be a genetic component. If your mother or sister had HG, your risk is higher. Research published in the British Journal of Obstetrics and Gynaecology and other journals has identified that women with a family history of HG are more likely to develop it themselves.

Recent research has also pointed to a specific protein called GDF15. Some studies suggest that women who develop HG may be particularly sensitive to this protein, which is produced by the placenta. This is an active area of research, and the full picture is not yet clear.

What is clear is that HG is not caused by stress, anxiety, or a negative attitude toward pregnancy. That outdated idea has been disproven.

What Are The Symptoms Of HG?

Symptoms typically begin between weeks 4 and 6 of pregnancy. They often peak between weeks 9 and 13. Some women improve by week 20. Others do not.

Common symptoms include:

• Nausea that does not stop and is not relieved by eating or resting
• Vomiting multiple times daily, sometimes more than three or four times
• Inability to keep down food or fluids for extended periods
• Weight loss of 5% or more of pre-pregnancy body weight
• Signs of dehydration such as dark urine, infrequent urination, or dizziness when standing
• Fatigue and weakness that interferes with daily activities
• Increased heart rate
• Low blood pressure
• Dry skin and lips
• Confusion or fainting in severe cases

Some women also produce excessive saliva, a symptom called ptyalism. This is not dangerous but adds to the discomfort.

If vomiting is accompanied by abdominal pain, fever, or blood in the vomit, seek immediate medical attention. These symptoms are not typical of HG and may indicate another condition.

How Is HG Diagnosed?

There is no single test for HG. Diagnosis is based on symptoms, physical examination, and laboratory tests that rule out other causes.

Your doctor will likely ask about the frequency of vomiting, whether you can keep down fluids, and how much weight you have lost. They may check your urine for ketones, which appear when your body is breaking down fat instead of using carbohydrates for energy. High ketone levels indicate your body is not getting enough nutrition.

Blood tests can check for electrolyte imbalances and assess kidney and liver function. These tests help determine how severe the dehydration is and guide treatment.

In some cases, an ultrasound is done to confirm the pregnancy is viable and to rule out conditions like a molar pregnancy, which can produce similar symptoms.

Other conditions that can cause severe nausea and vomiting include thyroid disorders, gallbladder disease, and gastrointestinal conditions. Your doctor may test for these if your symptoms do not follow the typical pattern of HG.

What Treatments Are Available For HG?

Treatment depends on severity. Early intervention improves outcomes, so do not delay seeking help.

Mild to moderate HG. For women who can keep some fluids down, treatment may start with dietary changes and over-the-counter options. Eating small, frequent meals. Avoiding strong smells. Staying hydrated with small sips of fluid throughout the day.

Vitamin B6 (pyridoxine) is often recommended. Some evidence supports its use for nausea in pregnancy, though results vary. The typical dose in clinical practice is 10 to 25 mg taken three or four times daily. Ginger is another option that some studies have found helpful for mild nausea, though evidence for severe HG is limited.

Moderate to severe HG. When vomiting is persistent and dehydration is a concern, prescription medications are usually needed. Several anti-nausea medications are considered safe in pregnancy.

Doxylamine combined with vitamin B6 has strong evidence of effectiveness. It is available in some countries as a delayed-release prescription product. Antihistamines, such as diphenhydramine, are sometimes used. Dopamine antagonists, including metoclopramide and prochlorperazine, are also common options.

Ondansetron is frequently prescribed for severe cases. It is highly effective at reducing vomiting. There has been debate about its safety in early pregnancy, particularly regarding a small increased risk of certain birth defects. The absolute risk is low, and for many women the benefit of preventing severe dehydration outweighs the risk. This decision should be made between a woman and her doctor.

Severe HG requiring hospitalization. When a woman cannot keep down any fluids, intravenous (IV) fluids are necessary to restore hydration. Electrolytes are replaced as needed. IV anti-nausea medications are given until vomiting is controlled.

Thiamine (vitamin B1) supplementation is important for women who have lost significant weight. Thiamine deficiency in HG can lead to a neurological condition called Wernicke’s encephalopathy, which is serious but preventable.

Some women require nasogastric or nasojejunal tube feeding if oral nutrition is not possible for an extended period. This is uncommon but can be life-saving in severe cases.

What Are The Risks Of Untreated HG?

Untreated HG can lead to serious complications. Severe dehydration can affect kidney function. Electrolyte imbalances, particularly low potassium, can affect heart function. Prolonged vomiting can damage the esophagus.

Nutritional deficiencies are a real concern. Women with HG may become deficient in thiamine, vitamin B12, vitamin B6, and other nutrients. These deficiencies can have consequences for both mother and baby.

Weight loss during pregnancy is concerning, particularly if it is significant. Some research has linked poor maternal weight gain with lower birth weight. However, the evidence on pregnancy outcomes for women with HG is mixed. Many women with HG go on to have healthy babies.

One of the most underrecognized impacts of HG is on mental health. HG is exhausting and isolating. Many women report symptoms of depression and anxiety during and after the illness. Some studies have found higher rates of postpartum depression among women who had HG. Seeking mental health support is not a sign of weakness—it is part of comprehensive care.

Can HG Be Prevented?

There is no proven way to prevent HG. Because the underlying cause is not fully understood, prevention strategies are limited.

For women who have had HG in a previous pregnancy, starting anti-nausea medication before symptoms become severe may help. Some doctors recommend beginning vitamin B6 and doxylamine as soon as pregnancy is confirmed, even before symptoms start.

Eating small frequent meals and staying hydrated before symptoms intensify may reduce the severity, though this has not been rigorously proven.

If you had HG before and are planning another pregnancy, discuss a management plan with your doctor before you conceive. Early treatment is associated with better outcomes.

When Should You Seek Medical Help?

Contact your doctor if you cannot keep down fluids for 12 hours or more. Seek help if you are vomiting more than three or four times a day and cannot function normally. Urgent evaluation is needed if you feel dizzy, faint, or confused, or if you are passing very little urine.

Do not wait until you are severely dehydrated. HG is treatable, and early treatment makes a meaningful difference in how you feel and how the pregnancy progresses.

If your current doctor does not take your symptoms seriously, seek a second opinion. HG is a recognized medical condition. You deserve care that addresses both the physical and emotional toll it takes.