ReproductiveICD-10: O21.0Uncommon; affects a small minority of pregnancies but is a leading cause of hospital admission in early pregnancy

Hyperemesis Gravidarum

Also known as: Severe pregnancy sickness, HG

Hyperemesis gravidarum (HG) is a severe form of nausea and vomiting in pregnancy that goes far beyond ordinary morning sickness. People with HG vomit repeatedly, struggle to keep down food or fluids, lose weight, and can become dehydrated and deficient in nutrients. It usually begins in the first trimester, often peaks around weeks 9 to 13, and improves for most by mid-pregnancy, though for some it persists until delivery. HG can be physically exhausting and emotionally isolating, and it sometimes requires hospital treatment with intravenous fluids. With proper care, outcomes for mother and baby are generally good, so early help should be sought rather than enduring it.

At a Glance

Common symptoms
Severe, persistent nausea and vomiting several times a day, Inability to keep down food or even fluids, Weight loss of more than about 5% of pre-pregnancy weight
Main treatments
Anti-sickness medications proven safe in pregnancy, such as pyridoxine with doxylamine, antihistamines, or ondansetron and others as prescribed, Intravenous fluids and electrolyte replacement for dehydration, Thiamine (vitamin B1) and other vitamin supplementation to prevent deficiency
Category
Reproductive · Uncommon; affects a small minority of pregnancies but is a leading cause of hospital admission in early pregnancy
See a doctor if
You cannot keep any fluids down for 12–24 hours

Symptoms

Severe, persistent nausea and vomiting several times a day
Inability to keep down food or even fluids
Weight loss of more than about 5% of pre-pregnancy weight
Signs of dehydration: dark urine, infrequent urination, dizziness, dry mouth
Extreme fatigue and difficulty functioning
Excess saliva and heightened sensitivity to smells
Low mood or anxiety related to the illness

Causes

  • Rapidly rising pregnancy hormones, particularly hCG and estrogen
  • A genetic predisposition; recent research links the hormone GDF15 to HG
  • Multiple pregnancy (twins or more) or molar pregnancy, which raise hormone levels
  • Possible contribution from Helicobacter pylori infection
  • Thyroid changes in early pregnancy

Risk Factors

  • HG in a previous pregnancy
  • A mother or sister who had HG
  • Carrying twins or multiples
  • History of motion sickness or migraine
  • First pregnancy

Diagnosis

  • Clinical assessment of vomiting frequency, weight loss, and dehydration
  • Severity scoring using a validated questionnaire (such as PUQE)
  • Blood tests for electrolytes, kidney function, thyroid, and liver function
  • Urine tests for ketones and infection
  • Ultrasound to confirm dates and check for multiple or molar pregnancy

Treatment

  • Anti-sickness medications proven safe in pregnancy, such as pyridoxine with doxylamine, antihistamines, or ondansetron and others as prescribed
  • Intravenous fluids and electrolyte replacement for dehydration
  • Thiamine (vitamin B1) and other vitamin supplementation to prevent deficiency
  • Acid-suppressing medication if reflux is contributing
  • Tube feeding or, rarely, intravenous nutrition for severe cases
  • Supportive: small, frequent, bland, cold meals and separating food from drink
  • Supportive: ginger and acupressure wristbands may ease mild nausea for some, but are not substitutes for medical treatment in HG

Prevention

  • Starting a daily multivitamin before conception is associated with less severe nausea
  • If you had HG before, discuss an early treatment plan with your doctor as soon as pregnancy is confirmed
  • Begin anti-nausea medication early rather than waiting for severe symptoms
  • Avoid known smell and food triggers where possible
  • Arrange practical and emotional support ahead of time

When to See a Doctor

  • You cannot keep any fluids down for 12–24 hours
  • You are losing weight or are vomiting more than three or four times a day
  • Signs of dehydration such as dark urine, dizziness, or fainting
  • Vomiting blood or severe abdominal pain
  • You feel unable to cope or are having thoughts of ending the pregnancy because of the sickness

Frequently Asked Questions

Related Conditions

Nausea and Vomiting

Digestive

Gestational Diabetes

Endocrine

Preeclampsia

Reproductive

Miscarriage

Reproductive

Hyperthyroidism

Endocrine

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