Background and prevalence
• Nausea and vomiting of pregnancy affects at least 50% of women in the first trimester of
pregnancy. Symptoms usually begin between 5 and 6 weeks with peak severity around week 11,
and in 90% of women these symptoms resolve by week 16.
• HG – persistent vomiting in pregnancy, which leads to weight loss of > 5% of pre-pregnancy
weight with electrolyte imbalance and ketonuria. HG affects 1% of pregnant woman.
• Pathogenesis of HG is poorly understood and the aetiology is likely to be multifactorial.

Risks or complications
Maternal
• Weight loss and muscle wasting.
• Mallory–Weiss tears and haematemesis.
• Thiamine deficiency – Wernicke’s encephalopathy – diplopia, abnormal ocular movements,
ataxia, and confusion. IV glucose may precipitate it. Thiamine replacement may improve the
symptoms but residual impairment is not uncommon.
• Korsakoff’s psychosis – retrograde amnesia, impaired ability to learn, and confabulation.
The recovery rate is only about 50%.
• Hyponatraemia – lethargy, seizures, respiratory arrest. Both severe hyponatraemia and
its rapid reversal may precipitate central pontine myelinolysis – spastic quadraparesis,
pseudobulbar palsy, and impaired consciousness.
• Other vitamin deficiencies – (cyanocobalamin and pyridoxine) can cause anaemia and
peripheral neuropathy.
• Maternal death.
Fetal – lower birth weight; fetal death in severe Wernicke’s encephalopathy.
Psychological impact
• Affects work and quality of life.
• Depression.
• Difficulties between partners.
• In some, the condition is so intolerable that they elect to have a termination of pregnancy.

Clinical features
• Severe and persistent nausea and vomiting leading to dehydration and weight loss.
• There may be ptyalism (inability to swallow saliva) and spitting.
• Signs of dehydration, tachycardia, and postural hypotension.

Differential diagnosis
• Urinary tract infection. • Hepatitis.
• Appendicitis. • Cholecystitis.
• Small bowel obstruction. • Pancreatitis.
• Thyrotoxicosis, gestational thyrotoxicosis.
• Hyperparathyroidism. • Diabetic ketoacidosis.
• Uraemia. • Addison’s disease.
• Iron supplementation.

Evidence round-up
• Systematic review – women with HG during pregnancy are more likely to have
a baby with low birthweight and premature birth. There is no association with
Apgar scores, congenital anomalies, or perinatal death.

Management

Dietary and lifestyle changes – no evidence to prove the effectiveness of dietary changes on
relieving symptoms.
Non-pharmacological therapies
• Emotional support with frequent reassurance and encouragement.
• Psychotherapy, hypnotherapy, and behavioural therapy may be helpful.
• Ginger, alternative therapies, such as acupuncture and acupressure, may be beneficial.

Management – if no relief with conservative measures
Start pharmacological treatment as soon as possible.

Antihistamines
• H1 receptor antagonists (dimenhydrinate, diphenhydramine, and
hydroxyzine) are considered safe in pregnancy, with no human
teratogenic potential.
• Consider them in the management of acute or breakthrough episodes
of HG.
• Avoid excessive dosing of H1 receptor antagonists by combining
different antihistamines in therapy.

Pyridoxine
• Effective in reducing nausea; no association with major
malformations.
• Pyridoxine monotherapy supplementation may be considered
as an adjuvant measure.
• Because the concerns about the possible toxicity of pyridoxine
in high doses have not yet been resolved, do not recommend
pyridoxine for the treatment for hyperemesis.

Ranitidine and omeprazole
• Used primarily to reduce oesophageal acid
reflux associated with HG.
• No evidence of increased risk of congenital
malformations.

Dopamine antagonist phenothiazines
• Phenothiazines (chlorpromazine, perphenazine, prochlorperazine, promethazine,
trifluoperazine) have been proven to be safe for use in pregnancy.
• Phenothiazines are safe and effective for severe HG.

Metoclopramide
• There is no association between the drug exposure during the first
trimester and congenital malformations.
• Metoclopramide is safe to be used for management of HG, although
evidence for efficacy is limited.

If no improvement
Admission to hospital – any woman unable to maintain adequate hydration.

Investigations
• Urea and electrolytes (U&E) – hyponatraemia, hypokalaemia.
• Raised haematocrit.
• Metabolic hypochloraemic alkalosis; severe cases – acidaemia.
• LFT – raised aminotransferase and bilirubin (frank jaundice is rare).
• Urinalysis – raised specific gravity and ketonuria.
• Urine microscopy and culture (M&C) – exclude UTI.
• USS – exclude molar or multiple pregnancy.
• TFT – raised free T4, reduced TSH – self-limiting. Routine
TFT is questionable as clinical hyperthyroidism does not occur
and treatment is not required. It may provide an index of severity
of HG, as women with abnormal thyroid function usually require
longer hospitalization to avoid readmission.

Rehydration
• IV rehydration with normal saline or Hartmann’s solution.
• Potassium chloride with each bag of saline, particularly if there
is continued vomiting.
• Fluid and electrolyte regimens must be adapted daily and
titrated against daily measurements of serum sodium and
potassium.
• Avoid double strength saline solution even in cases of severe
hyponatraemia, as rapid correction of sodium depletion may
cause central pontine myelinolysis.
• Avoid solutions containing dextrose because they do not contain
enough sodium and may precipitate Wernicke’s encephalopathy.

Monitoring and others
• Weight, pulse, and BP.
• Discontinue drugs that may cause nausea and
vomiting (e.g., iron supplements) temporarily.
• Routine thiamine supplementation to prevent
Wernicke’s encephalopathy; oral/IV.
• Thromboprophylaxis (e.g., enoxaparin 40 mg
daily) and thromboembolic deterrent stockings.

If no improvement Refractory – severe hyperemesis gravidarum

Ondansetron

Corticosteroid therapy

Evidence round up
Cochrane review, 2010 – acupressure, acustimulation, acupuncture, ginger, vitamin B6, and several antiemetic drugs:
• P6 acupressure, auricular acupressure, and acustimulation of the P6 point – limited evidence.
• Acupuncture – no significant benefit.
• Ginger products may be helpful, but the evidence of effectiveness is limited.
• Limited evidence to support the use of vitamin B6 and antiemetic drugs to relieve mild or moderate nausea and vomiting.
• Little information on maternal and fetal adverse outcomes on psychological, social, or economic outcomes.