How Do You Diagnose Hyperemesis (HG)?

Hyperemesis gravidarum (HG) begins between the fourth and sixth week of pregnancy. Half of women experience symptom resolution, or at least significant improvement, somewhere around 14-20 weeks; about 20% will continue to have significant nausea/vomiting until late pregnancy or delivery. For some, symptoms continue after delivery for weeks or months and continued treatment is needed. You can see a general idea of HG severity levels defined to understand better your HG



Most affected women have continuous nausea and multiple episodes of vomiting throughout the day with few if any symptom-free periods, especially during the first three months. This may lead to rapid and/or significant weight loss, dehydration, and electrolyte disturbances often requiring hospitalization.

If not treated promptly, methodically, and adequately, these can lead to fetal loss, and irreversible renal, neurologic, and hepatic damage, or even death

MORE ON: Signs & Symptoms and Lab Tests for HG

Severe HG

These women present to their physicians with weight loss of 5 to 20+ pounds (2.25 to 9+ kgs); however, those who are overweight may not appear malnourished. This is especially true as the pregnancy progresses. However, they still become vitamin deficient and at risk of serious complications (e.g. Wernicke’s encephalopathy) as soon as 2 weeks after reduced intake. 

Early, aggressive medical care often decreases the severity of a woman's symptoms and leads to quicker recovery.


Progression to HG

Recognizing a woman is transitioning from morning sickness to hyperemesis gravidarum is critical. The initial signs include: 

  • Weight loss (2+ lbs [1 kg] weekly) 
  • Recurrent ketosis 
  • Frequent and/or severe nausea/vomiting 
  • Dehydration 
  • Severe fatigue 
  • Inability to work 

If these are seen early in pregnancy, hydration with vitamins, antiemetics, and close monitoring is imperative. See our HG Treatment Protocol and Assessment Tools to determine HG severity and identify possible HG complications.


Risk Factors 

Study findings vary widely in determining the women most at risk for HG. It is more common in first pregnancies, and in women who weigh more than 170 pounds (77 kg), are nonsmokers, have twin (or more) pregnancies, trophoblastic disease, a high fat or low dairy diet, or are less than 20 years old. The risk may decrease after age 35. Hyperemesis often recurs in subsequent pregnancies in similar patterns. 

Most significant risk factor for HG is a female relative with HG. Read our HG genetic study.

Recurrence Rate

Our studies consistently find the recurrence risk exceeds 75%. Epidemiological studies indicate that women with mild nausea and vomiting in pregnancy have a statistically significant decrease in the risk of miscarriage in the first 20 weeks but may have a history of several spontaneous abortions (miscarriages). However, women with severe nausea and vomiting have a 33% risk of fetal loss. Patients who do not receive adequate treatment are found to have more losses and pregnancy termination (NCBI Study).


Research Limitations

Studies have been limited by the inconsistent criteria for diagnosing HG and the global knowledge deficit of proper treatment. Without effective care and support, women will progress to more severe symptoms. 


HER Assessment Tools

Assessing women with HG can be difficult due to fluctuating and complex symptoms. Thus, the HER Foundation developed important tools to help you effectively and efficiently evaluate HG patients. 


HELP Score

The HER Foundation’s HELP Score is a tool to quantify and monitor symptom severity, especially with more complex symptoms. 


  • Evaluation of key clinical concerns,
  • Quick identification of severe symptoms, and
  • Detection of changes in severity.

HG Assessment Packet

The HER Foundation developed a comprehensive assessment packet to promote standardized assessment of HG and improve recognition of comorbidities and developing complications. The Assessment Packet is divided into 3 parts: 

  1. Initial visit assessment,
  2. Per visit assessment, and
  3. Detailed care planning tool for clinicians.