Nausea and Vomiting and Hyperemesis Gravidarum in Pregnancy
RCOG Green-top Guideline No. 69 The Management of Nausea and Vomiting of Pregnancy and Hyperemesis Gravidarum. Last revised: Jun 2025.
NICE CKS Nausea / vomiting in pregnancy. Last revised: Apr 2025.
Background Information
Definition
Nausea and vomiting in pregnancy: if onset in 1st trimester and other causes are excluded
- Usually begins at 4-7 weeks of gestation, peaks at 9-16 weeks, and resolves by 16-20 weeks
- If onset >11 weeks → alternative cause likely
Hyperemesis gravidarum is the most severe spectrum of nausea and vomiting in pregnancy, defined by:
- Severe enough to affect eating and drinking normally, and
- Strongly limits daily activities of living
The diagnosis of hyperemesis gravidarum no longer requires the traditional triad of ≥5% weight loss + dehydration + electrolyte disturbance.
Complications
Metabolic complications
- Dehydration
- Weight loss
- Electrolyte imbalance – hyponatraemia, hypokalemia, metabolic hypochloraemic alkalosis
- Acute kidney injury
- Nutritional and vitamin deficiencies
- Vitamin B1 deficiency → life-threatening Wernicke’s encephalopathy
- Vitamin B6 and B12 deficiency → peripheral neuropathy
Mechanical complications
- Retinal haemorrhage
- Mallory-Weiss tears / oesophageal rupture
- Pneumothorax / pneumomediastinum
- Splenic avulsion
- GORD / oesophagitis, gastritis
Guidelines
Assessment
Nausea and vomiting in pregnancy and hyperemesis gravidarum are clinical diagnoses (see definition above).
Perform the following:
- History and examination (including temperature, blood pressure, pulse, oxygen saturation, respiratory rate, and weight)
- Urinalysis and MSU (if UTI suspected)
- Blood tests – FBC, U&E, blood glucose
- Ultrasound scan
- Consider TFT, LFT, amylase, calcium and phosphate in refractory cases / history of previous admissions
The diagnosis of hyperemesis gravidarum no longer requires the traditional triad of ≥5% weight loss + dehydration + electrolyte disturbance.
Note that RCOG says that ketonuria is NOT an indicator of dehydration and it is NOT associated with the severity of nausea and vomiting in pregnancy or hyperemesis gravidarum.
RCOG: Assessing urine ketones does not have a use in management and may be misleading.
Severity Assessment
The Pregnancy-Unique Quantification of Emesis (PUQE) tool can be used to classify the severity,
- ≤6 = mild
- 7-12 = moderate
- 13-15 = severe
Management
Inpatient care should be considered if ANY of the following is present:
- PUQE score ≥13
- Failed outpatient management
Refer for inpatient management if ANY of the following is present:
- Inability to tolerate oral intake
- Clinical dehydration
- >5% weight loss despite oral antiemetics
- Presence of co-morbidities (e.g. epilepsy, diabetes, HIV, hypoadrenalism, psychiatric disease)
- Concerns regarding mental health
Conservative Management (Outpatient)
- Rest as needed
- Avoid sensory stimuli (e.g. odours, heat, noise)
- Eat plain biscuits / crackers in the morning
- Bland, small, frequent protein-rich meals, low in carbohydrate and fat
- Drink little and often
- Acupressure (e.g., over P6 point)
Anti-Emetic Therapy
Most of the following can be given orally or parenterally (IM / IV / SC); alter route of administration depending on outpatient vs inpatient management.
- 1st line options:
- Antihistamines
- Pyridoxine–doxylamine (Xonvea®)
- Cyclizine
- Promethazine
- Prochlorperazine, chlorpromazine
- Antihistamines
- 2nd line options:
- Ondansetron (very small risk of orofacial clefting in 1st trimester, but should not be discouraged if 1st line failed)
- Dopamine antagonists (metoclopramide / domperidone)
- 3rd line: corticosteroids (IV hydrocortisone or oral prednisolone)
Additional Therapy (Inpatient)
The following should be given for inpatient care:
- Rehydration with IV 0.9% saline with additional potassium (dextrose is NOT recommended)
- Thiamine supplementation (oral or Pabrinex®)
- Thromboprophylaxis with LMWH (alternative: graduated compression stockings)
References
Original Guideline