Hyperemesis gravidarum: when nausea is not "normal"
Nausea during pregnancy is common, but when it becomes disabling it can be hyperemesis gravidarum. We explain how to tell them apart, when to see a doctor and what treatments exist.
If you are pregnant and have spent days unable to keep down even water, have lost weight and can barely get out of bed, what you are going through is probably not “the typical nausea of the first trimester”. It may be hyperemesis gravidarum, a real, recognised and treatable medical condition that affects between 0.3% and 3% of pregnancies according to data compiled by the Spanish Society of Gynaecology and Obstetrics (SEGO) and the American College of Obstetricians and Gynecologists (ACOG).
The problem is that many women wait weeks before asking for help because they have been told—sometimes even in the consulting room—that “you just have to put up with it during pregnancy”. No. Vomiting 20 times a day, becoming dehydrated and losing weight is not a normal part of pregnancy. Here you will find the criteria professionals use to diagnose it, the signs that mean you need attention now, and the treatment options available.
What hyperemesis gravidarum is
Hyperemesis gravidarum is a severe form of pregnancy nausea and vomiting that causes dehydration, weight loss and metabolic disturbances. It is not “strong nausea”: it is a clinical condition that usually requires medical treatment and, in the most intense cases, hospital admission for intravenous hydration.
It usually appears between weeks 4 and 6 of pregnancy, peaks around weeks 9–13 and in most cases improves from week 20 onwards. In a small percentage, symptoms persist throughout the whole pregnancy.
Quick facts
| Data | Value |
|---|---|
| Prevalence | 0.3% – 3% of pregnancies |
| Usual onset | Weeks 4–6 of gestation |
| Peak of symptoms | Weeks 9–13 |
| Usual improvement | From week 20 |
| Weight criterion | Loss > 5% of pre-pregnancy weight |
| Typical blood/urine tests | Ketonuria, electrolyte alterations |
Why it happens: causes of hyperemesis gravidarum
No single cause has been identified. Current evidence points to a combination of factors:
- Hormonal: elevated levels of hCG (human chorionic gonadotropin) and oestrogens. That is why it is more frequent in multiple pregnancies or gestational trophoblastic disease.
- Genetic: recent studies (Fejzo et al., Nature, 2023) have identified the GDF15 gene as a key factor in the development of hyperemesis.
- Personal or family history: if your mother or sister had it, your risk increases.
- Previous history: having had it in an earlier pregnancy greatly raises the likelihood of recurrence.
It is not caused by stress, by “thinking too much about the vomiting”, or by rejecting the pregnancy. This myth, sadly still widespread, has delayed diagnoses and treatments for decades.
Difference between normal pregnancy nausea and hyperemesis
This is the key question. Common nausea affects 70–80% of pregnant women and, although unpleasant, it allows people to continue with daily life. Hyperemesis does not.
| Characteristic | Common nausea | Hyperemesis gravidarum |
|---|---|---|
| Vomiting per day | Occasional, 1–3 | Persistent, >3–4 |
| Fluid intake | Tolerated | Not tolerated |
| Weight loss | None or minimal | > 5% of pre-pregnancy weight |
| Daily life | Limited but possible | Disabling |
| Dehydration | No | Yes (dark urine, dizziness) |
| Blood/urine tests | Normal | Ketonuria, abnormal ions |
Symptoms of hyperemesis gravidarum
The most frequent symptoms of hyperemesis gravidarum are:
- Persistent vomiting, several times a day, that prevents keeping fluids or food down.
- Weight loss of more than 5% compared with pre-pregnancy weight.
- Signs of dehydration: dry mouth, very scant and dark urine, dizziness on standing up, tachycardia.
- Extreme fatigue, difficulty getting out of bed.
- Excessive salivation (ptyalism).
- Extreme sensitivity to smells.
- In severe cases: altered taste, confusion, fainting.
When to see a doctor for nausea in pregnancy
Do not wait. Contact your midwife, your gynaecologist or go to the emergency department if:
- You have gone more than 24 hours without being able to keep down fluids.
- You have lost weight since the start of the pregnancy.
- Your urine is very dark or you barely pass urine.
- You have dizziness on standing, tachycardia or confusion.
- You vomit blood or material that looks like coffee grounds.
- You have fever or abdominal pain associated with it.
Untreated hyperemesis can lead to serious complications (Wernicke’s encephalopathy due to thiamine deficiency, liver abnormalities, thrombosis). This is not alarmism: treatment exists and it works.
Treatment of hyperemesis gravidarum
Treatment of hyperemesis gravidarum is stepped according to severity and is prescribed by your gynaecologist or emergency physician. Never self-medicate during pregnancy.
The SEGO and ACOG guidelines contemplate, as a general guide:
- Dietary and environmental measures: eat little and often, avoid trigger smells, separate solids from liquids, try ginger.
- Vitamin B6 (pyridoxine), alone or combined with doxylamine. First-line drug treatment according to ACOG.
- Antiemetics: metoclopramide, ondansetron or others, always on prescription.
- Intravenous hydration in a day unit or admission if there is dehydration or sustained ketonuria.
- Thiamine supplementation to prevent Wernicke’s encephalopathy.
- In refractory cases: enteral or parenteral nutrition.
The goal is not to “put up with it”, but for you to be able to eat, drink and rest.
Common myths
- “It is psychological”: false. It has a documented hormonal and genetic basis.
- “If you vomit a lot, the baby does not get fed”: in most cases the baby obtains nutrients from maternal reserves. What matters is treating the mother.
- “Antiemetics harm the foetus”: first-line drugs have a well-studied safety profile. The greater risk is not treating.
- “It will go away on its own”: sometimes it does, sometimes it does not. In the meantime, there is a solution.
If you are going through an emotionally complicated pregnancy, you may also find it helpful to read about employment rights and sick leave during pregnancy, since hyperemesis is a recognised cause of medical leave.
Frequently asked questions
Does hyperemesis affect the baby? If it is well treated, most babies are born healthy and at an appropriate weight. Without treatment and with significant maternal weight loss, it can be associated with low birth weight.
Will I have it again in the next pregnancy? The risk of recurrence is high (around 15–80% according to studies). If you are planning it, discuss it with your gynaecologist to prepare a plan from the outset.
Can I take sick leave? Yes. Hyperemesis gravidarum is a recognised medical cause of temporary incapacity. Your GP or gynaecologist can process it.
Does ginger help? It may help with mild nausea. In established hyperemesis it does not replace medical treatment, although it can complement it if your healthcare professional approves.
Where can I get emotional support? Experiencing hyperemesis is physically and mentally exhausting. Talking to your midwife, to support groups (such as the HER Foundation association) or to a perinatal psychologist can make a difference. You are not exaggerating and you are not alone.
