Hyperemesis Gravidarum

  • Regina LopesSenior Nursing Assistant, Health and Social Care, The Open University

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Behind the veil of pregnancy's celebrated glow lies a hidden struggle endured by many: hyperemesis gravidarum (HG). It isn't just a case of morning sickness. But it's persistent and severe nausea, vomiting potentially leading to dehydration and malnutrition. It challenges both the physical and emotional well-being of pregnant individuals.

As one of the most severe complications of pregnancy, HG not only threatens the health of the pregnant individual but also of the unborn child. As expectant individuals grapple with the overwhelming symptoms, the need for effective treatment and support becomes increasingly important.

Hyperemesis gravidarum (HG)

Between fifty to ninety percent of pregnant individuals experience nausea and vomiting during their first trimester. These symptoms, collectively referred to as nausea and vomiting of pregnancy (NVP). They manifest between the 4th and 6th week of gestational age, reaching a peak around weeks 8 to 12. However, in approximately 0.5 to 3 pregnancies, a more severe form of NVP occurs, which is known as hyperemesis gravidarum (HG).1 

Hyperemesis gravidarum (HG) refers to intractable vomiting during pregnancy leading to weight loss and volume depletion, resulting in ketonuria (high levels of ketone bodies in urine) and/or ketonemia (unusually high amount of ketone bodies in the blood).2 The condition further is subdivided into mild and severe. The severe form is associated with metabolic disturbances such as carbohydrate depletion, dehydration, or electrolyte imbalance. It can be debilitating, significantly impacting a pregnant individual's quality of life and their family's well-being. 

It is the most common indication for hospitalisation in the first half of pregnancy. After preterm labour, HG ranks as the second most common reason for hospitalisation during pregnancy.3

Aetiology of hyperemesis gravidarum (HG)

The exact cause of hyperemesis gravidarum remains unclear and is likely influenced by multiple factors. Risk factors of hyperemesis gravidarum (HG) include pregnancy at a young age, carrying a foetus assigned female at birth, multiple pregnancy, molar pregnancy, underlying medical conditions such as thyroid and parathyroid dysfunction, hypercholesterolemia, type 1 diabetes, or a previous history of HG.3,5

Human chorionic gonadotropin (hCG) levels peaking in the first trimester, have been associated with HG symptoms. Elevated estradiol (form of oestrogen) levels early in pregnancy coincide with nausea and vomiting. Hormonal changes in pregnancy relax the lower esophageal sphincter, potentially increasing symptoms of gastrointestinal reflux disease (GERD) like nausea.

Family history indicates increased risk of HG, with potential genetic links identified in genes GDF15 and IGFBP7. While these factors provide some understanding of the possible mechanisms behind HG, further research is needed to know its intricate causes fully.2

Symptoms of hyperemesis gravidarum (HG)

Hyperemesis gravidarum (HG) usually occurs during the first trimester, around six weeks of pregnancy. But symptoms can last weeks, months or up until delivery. The most common symptoms of HG are as follows:4

  • Severe nausea
  • Persistent and severe vomiting (more than three times per day)
  • Losing more than 5% of pre-pregnancy weight
  • Throwing up anything one tries to eat or drink
  • Dehydration
  • Less frequent urination
  • Extreme tiredness
  • Dizziness or lightheadedness
  • Fainting
  • Headaches

The less common symptoms are:

Risks of hyperemesis gravidarum (HG) in pregnant people

Hyperemesis gravidarum (HG) can severely impact pregnant people, potentially leading to malnutrition, electrolyte imbalances if not adequately managed. Malnourishment-related Wernicke encephalopathy in pregnancy is a serious consequence of HG, often resulting in rapid onset and a detrimental course. Although rare, extreme forms of HG can lead to severe malnutrition and end-organ damage manifesting as oliguria and abnormal liver function tests.3,5

A significant increase in the risk of autoimmune disorders is observed among pregnant people with HG. HG increases the risk of both antenatal and postnatal venous thromboembolism. Management of comorbidities like diabetes, epilepsy, HIV, autoimmune disorders, and psychiatric disorders can be challenging with HG, potentially leading to worsening conditions due to difficulty in medication intake. There are higher rates of depression, anxiety, post traumatic stress disorder (PTSD), cognitive, behavioural, and emotional dysfunction in pregnant people with HG.3,5

Suicidal thoughts can occur more often in those with HG compared to other pregnant women. More than half of HG patients might think about ending their pregnancy because of the condition. A significant proportion may proceed with termination due to HG alone. The health effects of HG can extend beyond pregnancy, with implications on family planning, including postponed or avoided pregnancies due to fear of recurrence.5 

Risks of hyperemesis gravidarum (HG) in pregnant people’s offspring

Individuals with hyperemesis gravidarum (HG) were more likely to experience adverse perinatal outcomes such as placental abruption, prematurity, small-for-gestational-age foetuses with low birth weight (<1500 g), preterm birth. Babies born to those with HG often need special care in the neonatal intensive care unit and sometimes require resuscitation. Vitamin deficiency in individuals with HG may lead to neonatal vitamin K deficiency. This affects clotting after birth and potentially contributes to foetal congenital abnormalities. Parental undernutrition and weight loss due to HG predisposes the offspring to health effects throughout their lives.3,5

HG might be associated with slight increases in anxiety disorders and sleep problems and a possible association with testicular cancer. Although this evidence is limited by the small number of studies and their quality. There is limited data on the long-term effects of HG on children into adulthood.5

Treatment of hyperemesis gravidarum (HG)

Hyperemesis gravidarum (HG) can be incredibly challenging to treat. Early intervention and support are essential for managing HG effectively. Treatment strategies for hyperemesis gravidarum (HG) encompass both inpatient and outpatient care. It involves intravenous fluids, pharmacological and non-pharmacological agents and dietary advice.

Vitamin B6 may help relieve mild or moderate nausea and vomiting. Antiemetic drugs commonly used for nausea and vomiting are not approved for pregnancy use. The only drug approved in the UK specifically for the treatment of nausea and vomiting of pregnancy is the delayed-release formulation of doxylamine succinate and pyridoxine hydrochloride.5

First-generation antihistamines may offer some relief but lack strong evidence. Promethazine, metoclopramide and ondansetron are used as alternatives. The concerns about ondansetron's safety in foetuses remain. The use of corticosteroids is reserved, especially in the first trimester, for patients whose symptoms are not adequately controlled with other antiemetics. There is insufficient evidence to determine which pharmacological agent is more effective and safer for both the pregnant individual and foetus.5

To avoid the development of Wernicke encephalopathy, it is recommended to provide thiamine supplementation to pregnant individuals experiencing extended periods of nutrient deprivation. Enteral tube feeding or total parenteral nutrition may be considered if necessary. Ginger products considered safe during pregnancy, might offer relief from mild nausea and vomiting. Individuals experiencing HG may find relief by avoiding triggers such as specific odours and foods.

Adopting low-energy, high-protein diets could potentially reduce nausea and vomiting compared to high-carbohydrate diets. Referral to a dietitian may be beneficial to prevent weight loss and malnutrition. Psychosocial support and prescription of antidepressants should be considered if the condition causes substantial psychological distress. This can help alleviate the impact of HG on mood and daily activities.3,5


Hyperemesis gravidarum (HG) causes adverse health outcomes in pregnant individuals and their offspring. While treatments primarily target symptom relief, their impact on enhancing perinatal outcomes is uncertain. Numerous inquiries regarding the prevention and management of hyperemesis gravidarum persist. There is an emphasis on the need to comprehend the condition's causes, its effects and develop better treatment modalities. 


  1. Lacasse A, Rey E, Ferreira E, Morin C, Bérard A. Epidemiology of nausea and vomiting of pregnancy: prevalence, severity, determinants, and the importance of race/ethnicity. BMC Pregnancy Childbirth [Internet]. 2009 [cited 2024 May 25]; 9:26. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2713199/.
  2. Jennings LK, Mahdy H. Hyperemesis Gravidarum. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 [cited 2024 May 25]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK532917/.
  3. Lutomski J, McCarthy FP, Greene RA. Hyperemesis gravidarum: current perspectives. IJWH [Internet]. 2014 [cited 2024 May 25]; 719. Available from: http://www.dovepress.com/hyperemesis-gravidarum-current-perspectives-peer-reviewed-article-IJWH.
  4. Hyperemesis Gravidarum: Do You Have It? Cleveland Clinic [Internet]. [cited 2024 May 25]. Available from: https://my.clevelandclinic.org/health/diseases/12232-hyperemesis-gravidarum.
  5. Jansen LAW, Shaw V, Grooten IJ, Koot MH, Dean CR, Painter RC. Diagnosis and treatment of hyperemesis gravidarum. CMAJ [Internet]. 2024 [cited 2024 May 25]; 196(14):E477–85. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11019608/.

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Nirainila Antony Joseph

Bachelor of Dental Surgery (BDS), Tamil Nadu Government Dental College and Hospital, India

Master of Science (MS), Institute of Oral Medicine, National Cheng Kung University, Taiwan

Dr. Nirainila is a general dentist with extensive experience in comprehensive dental care and patient education. She is also a dedicated researcher focusing on dental aerosols, investigating their implications and control strategies within dental settings. Alongside her clinical and research endeavors, she is a medical content writer who simplifies complex medical information into reader-friendly articles, making health education accessible to a broader audience.

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