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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

Nausea and vomiting in pregnancy: if onset in 1st trimester and other causes are excluded
  • Usually begin 4-7 weeks of gestation, peak 9-16 weeks, and resolve 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.

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

Nausea and vomiting in pregnancy and hyperemesis gravidarum is a clinical diagnosis (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 is 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.

The Pregnancy-Unique Quantification of Emesis (PUQE) tool can be used to classify the severity, 

  • ≤6 = mild
  • 7-12 = moderate
  • 13-15 = severe

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 anti-emetics
  • Presence of co-morbidities (e.g. epilepsy, diabetes, HIV, hypoadrenalism, psychiatric disease)
  • Concerns regarding mental health
 

  • 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)

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:
    • Pyridoxine (vitamin B6)-doxylamine (Xonvea®)
    • Anti-histamines (cyclizine, promethazine)
    • Prochlorperazine, chlorpromazine
 
  • 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)

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

Author: Adams Lau
Reviewer:
Last edited: 03/07/25