HG in pregnancy stands for hyperemesis gravidarum, a severe form of nausea and vomiting that goes far beyond typical morning sickness. It’s defined by a triad of symptoms: dehydration, weight loss of more than 5% of pre-pregnancy body weight, and electrolyte imbalances. For someone who weighed 140 pounds before pregnancy, that means losing 7 or more pounds from vomiting alone. HG affects a small percentage of pregnancies, but for those who experience it, the condition can be debilitating and sometimes dangerous.
How HG Differs From Morning Sickness
Most pregnant people experience some nausea during the first trimester. Morning sickness is uncomfortable, but it generally doesn’t prevent you from keeping food and fluids down most of the time. HG is a different category entirely. The vomiting is relentless, typically more than three times a day, and it doesn’t respond to the usual remedies like ginger tea or small frequent meals.
The key distinction is what happens to your body as a result. With morning sickness, you may feel miserable but you maintain your weight and stay hydrated. With HG, the vomiting is severe enough to cause measurable weight loss, and your body starts running low on essential minerals like potassium, magnesium, and phosphorus. You may not be able to keep down water, let alone food, for hours or even days at a time. That level of fluid loss leads to dehydration that shows up in dark urine, dizziness, rapid heart rate, and fainting.
When Symptoms Typically Start and End
HG usually begins in the first trimester, around the same time morning sickness kicks in. For most people, symptoms improve significantly by weeks 16 to 18 of pregnancy. Cases that persist beyond that point are uncommon but carry higher risks, including liver damage and a serious neurological condition caused by vitamin B1 deficiency. Some people do experience symptoms throughout their entire pregnancy, though this is rare.
What Causes It
The exact cause of HG isn’t fully understood, but recent genetic research has pointed to a hormone called GDF15 as a major player. This protein, produced by the placenta, surges during pregnancy and triggers the nausea response in the brain. Some people appear to be more sensitive to GDF15 than others, which may explain why HG runs in families and why the severity varies so dramatically from one pregnancy to the next.
Researchers at the University of Southern California recently identified six genetic links to pregnancy sickness and have received approval to test an intriguing prevention strategy. The idea is that taking a common diabetes medication before pregnancy could gradually raise GDF15 levels ahead of time, essentially desensitizing the body so the sudden spike during early pregnancy isn’t as overwhelming. That trial is specifically aimed at people who have had HG in a previous pregnancy.
How Severity Is Measured
Healthcare providers often use a standardized scoring tool to assess how severe your nausea and vomiting are. Scores from 3 to 6 indicate mild symptoms, 7 to 12 moderate, and 13 or above severe. This helps determine whether you can manage symptoms at home or need hospital-based treatment. The score takes into account how many hours per day you feel nauseated, how frequently you vomit, and how many times you retch without actually vomiting.
What Treatment Looks Like
Mild HG can sometimes be managed at home with anti-nausea medications, dietary changes, and oral rehydration. But moderate to severe cases often require trips to the hospital or emergency room for intravenous fluids. When you can’t keep anything down for days, IV hydration is the fastest way to correct dehydration and replenish the minerals your body has lost. Potassium, magnesium, and phosphorus are the electrolytes most commonly depleted.
One important detail about hospital treatment: if you’re given IV fluids containing sugar, providers should give you vitamin B1 (thiamin) first. Severe, prolonged vomiting can deplete your thiamin stores, and administering sugar without replacing thiamin first can trigger a rare but serious brain condition called Wernicke encephalopathy. This is a well-known protocol, but it’s worth being aware of.
Some people with HG need multiple hospital visits or even extended stays. Others receive IV fluids at home through a portable setup. Anti-nausea medications are the backbone of ongoing management, and finding the right one often takes trial and error. What works well for one person may do nothing for another.
Risks of Untreated or Prolonged HG
When HG is recognized and treated, most people recover fully and deliver healthy babies. The danger comes from prolonged, undertreated cases. Persistent dehydration and malnutrition can lead to serious complications: liver damage, a rapid heart rate that doesn’t resolve, jaundice, and the thiamin-deficiency brain condition mentioned above. In extremely rare cases, severe vomiting can cause tears in the esophagus.
There’s also a significant psychological toll. HG can be isolating, especially when the people around you dismiss it as “just morning sickness.” Many people with HG are unable to work, care for other children, or maintain daily routines for weeks or months. Depression and anxiety during and after an HG pregnancy are common, and some people choose not to have additional pregnancies because the experience was so traumatic.
Signs You May Have HG, Not Morning Sickness
- Weight loss: You’ve lost more than 5% of your pre-pregnancy weight.
- Frequency: You’re vomiting more than three times a day, most days.
- Dehydration: Your urine is very dark, you feel dizzy when standing, or you can’t keep fluids down for 12 or more hours.
- Duration: Symptoms aren’t improving by the end of the first trimester and may be getting worse.
- Function: You’re unable to eat, drink, or carry out basic activities.
If this sounds like what you’re going through, it’s not something you need to push through on your own. HG is a recognized medical condition with real physiological causes, and effective treatment exists to protect both you and your pregnancy.