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About Hyperemesis Gravidarum (HG)

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Why HG Is So Important to Us

HG is an area of high unmet need where treatment expertise is scarce

  • A lack of disease awareness means it's severely under diagnosed

  • The emergency room is the primary treatment center for many HG patients 

  • Poor disease management significantly impacts the health of both mother and baby

Incidence of Hyperemesis Gravidarum 

The criteria used to diagnose hyperemesis gravidarum (HG) often varies among health professionals and researchers. It's vastly under diagnosed and not really a rare disorder. Patients who are very severe are typically hospitalized, representing the 1-3% of pregnancies estimated as having HG. However, very little research is done on the impact of hyperemesis as differentiated from morning sickness; thus the impact of HG is likely greatly underestimated. One study by Zhang, et al found a 10.8% incidence of severe vomiting, and another study found 16% of pregnant patients using antiemetics.


There are hundreds, if not thousands, of additional people who terminate their pregnancy out of desperation when given inadequate treatment despite debilitating symptoms.

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“A large majority (82.8%) reported that HG caused negative psychosocial changes, consisting of (1) socioeconomic changes, for example, job loss or difficulties, (2) attitude changes including fear regarding future pregnancies and (3) psychiatric sequelae, for example, feelings of depression and anxiety, which for some continued postpartum. Patients who reported that their health-care provider was uncaring or unaware of the severity of their symptoms were nearly twice as likely to report these psychiatric sequelae.”

Impact of Hyperemesis Gravidarum 

Research finds that the greater the severity and duration of symptoms, the greater the effect on both mom and baby.

Nausea and vomiting during pregnancy (NVP) can be mild (morning sickness) or more severe (hyperemesis gravidarum). NVP impacts every aspect of a woman's life.

    • 76.0% reported changes in their plans for future childbearing.  

    • 19.4% developed a fear of pregnancy, and some specifically developed a fear of having sex.  

    • 34.8% changed their mind regarding or considered limiting the number of children they planned to conceive. 

    • 28.7% of patients reported that their health-care providers were either uncaring or did not understand. 

    • Several used adoption or surrogacy to reach their family goals or increased the spacing of their pregnancies. 

    • 15.2% voluntarily terminated at least one pregnancy because of HG. 

    • 6.7% reported serious psychological sequelae from their HG experience. 

    Source: Journal of Perinatology (2008) 28, 176–181.

Risks and Outcomes of Hyperemesis Gravidarum

Research shows that patients with hyperemesis gravidarum (HG) have a higher risk of negative maternal and fetal outcomes. The greatest risk appears to be in patients who have more weight loss, severe symptoms, and/or who fail to gain weight for two consecutive trimesters. The data varies partly due to the inconsistent criteria used to diagnose and define hyperemesis (HG) and determine severity levels.

Recent consensus by ICHG (International Collaboration for Hyperemesis Gravidarum) on a definition for HG will help bring uniformity to future research. 

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Is Medication the Right Treatment?

One challenge with HG is weighing the risks of potential complications and misery with possible risks of anti-vomiting (antiemetic) therapies. Effective medications held until conservative measures fail delay needed treatment and may make vomiting more refractory.

There are a number of medications deemed safe with a long history of use. Yet, newer drugs often prove more effective, and do not significantly increase malformation rates

Although medication research is increasing (e.g. ondansetron) most studies find risks to be very small. Unfortunately, published abstracts sometimes make the risk unclear. For example, one widely cited study finds a risk of cardiac defects, but the low rate doubled to less than 2%. Health professionals need to review the detailed data to determine the unique risk/reward profile for their patients. 

Potential Fetal Complications and Outcomes of Hyperemesis Gravidarum

Beyond the fetal loss rate of 34%,  children are at risk for numerous complications from hyperemesis gravidarum (HG), especially if the symptoms are severe, prolonged, inadequately treated, or there is a delay in medical intervention. Specifically, weight loss over 15% of pre-pregnancy weight is highly predictive of adverse fetal impact. 

The exact causation is not entirely clear but high cortisol levels and stress, micronutrient deficiencies (vit K embryopathy, Wernicke’s encephalopathy), and inadequate maternal support, resources and access to care all play a role. Some problems may also be related to specific issues (e.g. IV infection, emboli, medication side-effects). Effective and timley care is crucial. 

If HG patients are given early medical care enough to manage their symptoms and minimize nutritional deficiencies, both mother and child will be healthier now and in the future. 
"The adverse health consequences for mother and child, as well as the costs of healthcare and lost productivity, affect families, the community, and the nation. These patients and their children deserve excellent care and a chance at a healthy future.''

Kimber MacGibbon, RN
HER Co-Founder/Director

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What causes Hyperemesis Gravidarum?

There are numerous theories regarding the etiologies of HG; however, only one is, as of yet, conclusive. A cause of HG is very difficult to determine and likely multifactorial including hormones and digestive function. Additionally, causes may vary between patients depending on biological make-up (genetics), body chemistry, fetal gender, and overall health. Ther HER Foundation's collaborative genetics research definitively identifies genetic causes (e.g. GDF15 and PGR) influencing HG symptoms.

*Content on this page has been supplied and sourced with the consent of our resource partner the HER Foundation.

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