Understanding Hyperemesis Gravidarum

by Ann Marie King, Co-Founder, HER Foundation
and Marlena Fejzo, PhD, Geffen School of Medicine, UCLA

The world recently celebrated the news that Kate Middleton, Duchess of Cambridge, is expecting a baby. We also learned that the Duchess suffers from hyperemesis gravidarum (HG). Most people had never heard of this pregnancy complication, and much of the media misrepresented Kate’s ailment as “morning sickness.”

Mothers who have suffered from HG will attest that referring to HG as “morning sickness” is like calling a hurricane a light rain. While hyperemesis gravidarum does share some symptoms with the first-trimester “morning sickness” experienced during 70% of healthy pregnancies, the comparison is grossly misrepresentative.

In fact, hyperemesis gravidarum is the recognized diagnosis of a debilitating and potentially life-threatening pregnancy disease marked by rapid weight loss, malnutrition, and dehydration due to unrelenting nausea and/or vomiting. The severity and duration of HG varies, but it prevents women from performing their regular daily routines; creates persistent physical and emotional distress; and is linked to significant costs for fetal health, maternal health, and the economic wellbeing of families and communities.

At the HER (Hyperemesis Education & Research) Foundation, we’ve heard from thousands of women seeking help, compassion, and hope. During what should be a joyful time, expectant moms suffering from hyperemesis gravidarum often feel trivialized and unsupported, even by the healthcare professionals treating them. Many report a lack of consistent, proactive medical treatment for their hyperemesis, while symptoms worsen and health complications escalate. We’ve found that one of the most important factors in making it through an HG pregnancy – and one of the challenges – is a woman’s access to a healthcare team whose members are aware of the latest HG research and treatments, and who show compassion for HG patients. It is heartbreaking that many women come to us ready to terminate their wanted, planned pregnancies because they and their families are desperate for physical and emotional relief. The HER Foundation works to help these women find an HG-friendly physician and support network to avoid this outcome.

Women who have suffered from hyperemesis are begging for answers as they recover from devastatingly difficult pregnancies, and with the knowledge that they face an 80% risk of experiencing HG again in future pregnancies. More than 75% of HG women decide to reduce their family size because of the condition’s debilitating impact and the lack of effective treatment.

Advancing research on this little-understood condition is critical. Toward this goal, the HER Foundation just funded the first-ever HG genome project at UCLA, led by Harvard-trained geneticist Dr. Marlena Fejzo, herself an HG survivor and a member of HER’s Advisory Board. Together, we want to share the reasons why HG awareness, education, and research is desperately needed:


  • HG babies are at increased risk for low birth weight, small for gestational age, and preterm birth.
  • Prolonged nausea is associated with behavioral and learning problems in children.
  • In utero exposure to HG is linked to a 3.6-fold increased risk of emotional/behavioral disorders.
  • 15% of HG pregnancies are lost to therapeutic terminations, citing “no hope for relief,” and current treatments are not adequate to prevent termination of these planned, wanted pregnancies.


  • Complications including retinal detachment, eardrum damage, loss of fingernails due to malnutrition, rib fractures, esophageal tears, and some deaths have been reported in the U.S. from HG complications.
  • Risk of Wernicke’s encephalopathy, a neurological syndrome caused by thiamine deficiency in HG pregnancies.
  • Complications such as dehydration pose a serious threat for mothers without access to immediate medical care, including low-income women and those in developing nations.
  • 18% of women report full criteria of post-traumatic stress disorder (PTSD) following an HG pregnancy.


  • In 2009, the cost of inpatient treatment for HG in the U.S. was over $250,000,000.
  • Additional cost of 225,000 HG emergency department visits in the U.S. annually.
  • Costs for ER visits, home health care, and administration of more expensive treatments such as TPN and Zofran to treat HG are rising.
  • Time lost from work for both the HG mom and her partner, childcare costs for siblings during a mom’s HG pregnancy, and costs due to long-term maternal and child health problems may be significant.

It’s our hope that the Duchess of Cambridge’s high-profile pregnancy will help to raise awareness of HG among both the general public and the maternal-child health community. Research funding is needed to better understand the causes of HG and to develop more effective treatments. And thousands of women suffering from HG each year continue to need support, information, and compassion.

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