Further guidance on the management of nauseas and vomiting in pregnancy can be accessed from the Royal College of Obstetricians and Gynaecologists or NICE CKS. The UK teratology information service website Best Use of Medicines in Pregnancy (BUMPS) is also useful.

Nausea and vomiting in pregnancy (NVP) is usually diagnosed in the first trimester and other causes have been excluded. It usually begins between 4–7th weeks, peaks between 9–16th weeks, and resolves by 16–20 weeks of pregnancy.

Hyperemesis gravidarum (HG) describes the most severe spectrum of symptoms, and is a clinical diagnosis of exclusion characterised by:

• Prolonged, persistent and severe nausea and vomiting unrelated to other causes.
• Weight loss (usually at least 5% of pre-pregnancy body weight).
• Dehydration and electrolyte imbalance.

Women with mild to moderate nausea and vomiting in pregnancy (PUQE score 3-12 (see below) and no dehydration) should be managed in primary care.

• Reassure – mild-to-moderate symptoms are common in pregnancy and usually resolve by 16–20 weeks of gestation.
• Rest – as needed and try to avoid sensory stimuli that may trigger symptoms, such as odours, heat, and noise. Fatigue exacerbates symptoms, support from family and friends with household chores and childcare can be helpful.
• Diet – drinking little and often, eating bland, small frequent protein-rich meals which are low in carbohydrate and fat. Eating plain biscuits or crackers in the morning. Cold meals may be more easily tolerated if nausea is smell related.
• Acupressure at wrist (P6) – some randomised controlled trials (RCT) and systematic reviews have suggested a beneficial effect
• Ginger – was superior to placebo in some studies, and may be effective (can be taken in fresh, tea, capsule, or syrup form).

Do not use diazepam, pyridoxine (monotherapy), herbal treatments, homeopathy, hypnotherapy, hypnosis, or psychotherapy. For further information on the formulary position on the use of herbal treatments and homeopathy, click here.

Where rest and dietary advice have been unsuccessful, early use of oral anti-emetics is recommended; these may reduce the risk of developing hyperemesis gravidarum.

NICE has produced a table of advantages and disadvantages of different pharmacological treatments for nausea and vomiting in pregnancy.

1st line

Promethazine hydrochloride

(Antihistamine)

• Initially 25mg at night; can be increased to 25mg morning and evening (off-label)
• See 3.4.1 antihistamines
• For patient information, refer to BUMPS

OR

Cyclizine

(Antihistamine)

• 50mg up to three times daily (off-label)
• See 4.6 Drugs used in nausea and vertigo
• For patient information, refer to BUMPS

Note: these may cause sedation and other antimuscarinic side effects.

Review after 24-72 hours and if response is good, continue treatment and reassess weekly thereafter. It may be possible to stop anti-emetics at 12-16 weeks, using clinical judgement.

Consider adding drugs rather than replacing them with different classes of drugs as different classes of drugs may have a synergistic effect.

• Many women will require more than one antiemetic to control their symptoms.
• Some women will require a combination of 3 or more antiemetics to control their symptoms.

If 1^st line anti-emetics are not effective and the woman is not dehydrated, consider 2^nd line anti-emetics.

2nd line

Doxylamine / pyridoxine

(Antihistamine / vitamin B6)

• 20/20mg (two tablets) once daily at bedtime for 2 days,
• increased on day 3 if necessary to 10/10mg (one tablet) in the morning and 20/20mg (two tablets) at bedtime,
• further increased on day 4 if necessary to 10/10mg (one tablet) in the morning, 10/10mg (one tablet) mid-afternoon and 20/20mg (two tablets) at bedtime.
• Maximum four tablets per day.
• To be taken on an empty stomach with a glass of water.
• Doxylamine/pyridoxine is considerably more expensive than other antiemetics that have long been used off-label for nausea and vomiting in pregnancy (NVP) but is the only licensed product for NVP in the UK.
• See 4.6 Drugs used in nausea and vertigo
• For patient information, refer to BUMPS

OR

Metoclopramide

(Dopamine receptor antagonist)

• 5-10mg three times a day for a maximum of 5 days (not for patients under 20 years old) (off-label)
• See 4.6 Drugs used in nausea and vertigo
• For patient information, refer to BUMPS

OR

Prochlorperazine

(Antipsychotic)

• Oral tablets: 5-10mg up to three times a day (off-label)
• Buccal tablets: 3-6mg twice daily (off-label)
• See 4.6 Drugs used in nausea and vertigo
• For patient information, refer to BUMPS

Note: there is an increased risk of extrapyramidal side effects and oculogyric crises with both metoclopramide and prochlorperazine.

If symptoms respond to second-line treatment, continue and review the woman once a week thereafter, depending on clinical judgement. It may be possible to stop anti-emetics at 12-16 weeks, using clinical judgement.

Consider adding drugs rather than replacing them with different classes of drugs as different classes of drugs may have a synergistic effect.

• Many women will require more than one antiemetic to control their symptoms.
• Some women will require a combination of 3 or more antiemetics to control their symptoms.

3rd line

Ondansetron

(Serotonin (5HT3) receptor antagonist)

• 4mg up to twice daily (off-label)
• Preferably not in the first trimester.
• Oral ondansetron should not be prescribed for longer than 5 days, exposure to ondansetron during the first trimester of pregnancy is associated with a small increased risk of the baby having a cleft lip and/or palate.
• See 4.6 Drugs used in nausea and vertigo
• For patient information, refer to BUMPS

Notes:
Patients must be counselled regarding the benefits of ondansetron together with the small increase in risk of orofacial cleft following use in the first 12 weeks of pregnancy. The background risk for orofacial cleft is 11 per 10,000 pregnancies. The risk of orofacial cleft is 14 per 10,000 pregnancies following ondansetron use in the first trimester. This equates to an additional 3 cases of orofacial cleft per 10,000 pregnancies exposed to ondansetron. 

For advice on prescribing ondansetron, see MHRA Drug Safety Update (January 2020): ondansetron small increased risk of oral clefts following use in the first 12 weeks of pregnancy

Ondansetron must not be used in patients with any history suggestive of prolonged QT; co-administration with other medicines which prolong the QT interval should be avoided.

If symptoms respond to treatment, continue, and review the woman once a week thereafter, depending on clinical judgement. It may be possible to stop anti-emetics at 12-16 weeks, using clinical judgement.

Consider adding drugs rather than replacing them with different classes of drugs as different classes of drugs may have a synergistic effect.

• Many women will require more than one antiemetic to control their symptoms.
• Some women will require a combination of 3 or more antiemetics to control their symptoms.

If oral anti-emetics are unsuccessful, or cannot be kept down, consider referral.

Corticosteroids

Corticosteroids should be reserved for cases where standard therapies have failed; when initiated they should be prescribed in addition to previously started effective antiemetics. Women taking corticosteroids may have an increased risk of hypertension and should be managed with increased caution and be screened for gestational diabetes.

Intravenous therapy is initiated in secondary care. Patients may be switched to oral therapy and continued in primary care, provided that they are improving clinically and are able to tolerate an oral formulation.

Prednisolone

(oral)

• 40-50mg once daily
• The steroid dose should be gradually tapered (by 5-10mg per week) until the lowest maintenance dose which controls symptoms has been reached.
• In some extreme cases, prednisolone is continued until birth.
• Stop if no benefit in 48 hours.
• See 6.3.2 Glucocorticoid therapy
• For patient information, refer to BUMPS

Pregnancy Unique Quantification of Emesis (PUQE) index

Severity of symptoms can be quantified using the Pregnancy Unique Quantification of Emesis (PUQE) index:

Motherisk PUQE-24 Scoring system

PUQE-24 score: Mild ≤ 6, Moderate = 7-12, Severe = 13-15 

Referral

Secondary care management usually takes the form of outpatient visits, rather than inpatient care, and may include daily saline infusions for dehydration.

Consider referral if the woman has persistent moderate-to-severe nausea and vomiting or hyperemesis gravidarum (HG)