Hyperemesis gravidarum

Hyperemesis gravidarum is extreme and persistent nausea and vomiting during pregnancy. It can lead to dehydration, weight loss and electrolyte imbalances.

Most women have nausea or vomiting (morning sickness), particularly during the first 3 months of pregnancy. The exact cause of nausea and vomiting during pregnancy is unknown. However, it is believed to be caused by a rapid increase in the blood level of a hormone called human chorionic gonadotropin (HCG). HCG is released from the placenta. Mild morning sickness is common. Hyperemesis gravidarum is less common and more severe.

Women with hyperemesis gravidarum have extreme nausea and vomiting during pregnancy. It can cause weight loss of more than 5% of body weight. The condition can occur in any pregnancy, but it’s a little more likely if you’re pregnant with twins (or multiple babies) or if you have a molar pregnancy. Women are at greater risk of hyperemesis if they have had the problem in previous pregnancies or are prone to motion sickness, a movement disease commonly called motion sickness or even seasickness, airsickness, train sickness.

Hyperemesis gravidarum vs morning sickness

Morning sickness Hyperemesis gravidarum
Nausea sometimes accompanied by vomiting Nausea accompanied by severe vomiting
Nausea that disappears at 12 weeks or soon after Nausea that does not subside
Vomiting that does not cause severe dehydration Vomiting causing severe dehydration
Vomiting that allows you to hold on to some food Vomiting that does not allow you to keep any food


While nausea and vomiting in pregnancy in general is estimated to occur in 50-90% of all pregnancies, hyperemesis gravidarum is estimated to occur in 0.5-2% of pregnant women. Hyperemesis gravidarum (usually) affects her only during the first trimester.

Symptoms of hyperemesis gravidarum

Hyperemesis gravidarum usually occurs during the first trimester of pregnancy. You may have hyperemesis gravidarum if you are pregnant and:

  • vomit 3-4 times a day or more;
  • you vomit so much that you lose more than 10 kilos;
  • you vomit so much that you feel dizzy;
  • you vomit so much that you become dehydrated;
  • you have a drop in blood pressure (hypotension)

Talk to your GP or midwife if you suffer from severe nausea and vomiting. Getting help beforehand can help you avoid dehydration and weight loss.

Other symptoms you may experience:

  • extremely pronounced sense of smell;
  • excessive saliva production;
  • headache and constipation from dehydration;

Risk factors for hyperemesis gravidarum

The following are risk factors for hyperemesis gravidarum:

  • a hyperemesis gravidarum during a previous pregnancy;
  • an overweight condition;
  • a multiple pregnancy;
  • a molar pregnancy;
  • the presence in the family of women who have had this condition;

Risks to the fetus and the future unborn child

HG can make you feel very sick, but it is unlikely to harm your baby if treated effectively.

However, if it causes you to lose weight during pregnancy, there is an increased risk that your baby may be born smaller than expected (having a low birth weight).


The diagnosis of hyperemesis gravidarum could lead to immediate hospitalization in order to restore fluids and replace electrolytes by infusing medications and fluids through the veins (intravenously).

Vitamin supplementation (especially vitamins B6, C and thiamine) may also be recommended.

With these treatments, in many cases, vomiting can stop. If vomiting persists, antiemetic drug therapy may be recommended.

More severe cases of hyperemesis gravidarum may require the administration of complex and balanced nutrient solutions through an IV during pregnancy. This is called total parenteral nutrition.


Although there are no known ways to completely prevent hyperemesis gravidarum, the following measures could help prevent morning sickness from becoming severe:

  • eat small and frequent meals.
  • eat bland foods.
  • Wait until the nausea has improved before taking iron supplements.
  • Using an anti-nausea bracelet

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform, Maternicity.com.

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