Management of pregnancy associated emesis

Nausea during the first trimester of pregnancy does NOT require pharmacological intervention. Severe vomiting is associated with multiple pregnancy and hydatidiform moles and these need to be excluded.

Usually nausea and vomiting improve after 14-16 weeks of pregnancy although many women will experience more nausea, and occasionally vomiting, whilst pregnant than during non-pregnancy.

Symptoms can usually be controlled by dietary measures e.g. avoidance of greasy foods and having frequent small meals. If vomiting is severe then treatment with an antihistamine (e.g. promethazine teoclate at an initial dose of 25 mg at bedtime) may bring symptomatic relief. Alternative antiemetics such as metoclopramide and prochlorperazine are often used.

NICE suggest that (1):

• if a woman requests or would like to consider treatment, the following interventions appear to be effective in reducing symptoms:
  • non-pharmacological
    • ginger
    • P6 acupressure
  • pharmacological
    • antihistamines.

If the woman is becoming dehydrated (ketones in urine) then admission to hospital is required. In hospital the woman is treated with intravenous fluids and is initially made nil by mouth. Antiemetics are given either intramuscularly or intravenously. There is generally symptomatic improvement by 24-36 hours and a light diet can be introduced. The patient is discharged when symptoms have resolved.

Whilst managing hyperemesis in pregnancy one should always consider pregnancy related causes of hyperemesis (e.g. multiple pregnancy) and causes of hyperemesis predisposed to by pregnancy (e.g. urinary tract infection).

Notes:

• thyroid function should be assessed in all women with hyperemesis gravidarum. This is because hyperthyroidism may result from higher serum concentrations of BHCG, which has TSH-like activity. Generally, hyperthyroidism associated with increased levels of BHCG resolves spontaneously after the first trimester (2). If hyperthyroidism is detected then initially supportive treatment is recommended. If the condition is persistent or severe then treatment with thionamides e.g. propylthiouracil, may be recommended
• use of prednisolone in the treatment of hyperemesis gravidarum
  • there is evidence that promethazine reduces the symptoms of hyperemesis gravidarum faster than prednisolone, but during prolonged treatment, prednisolone has at least the same effects on the symptoms and less drug side-effects (3)
• there is evidence concerning the efficacy of both pyridoxine hydrochloride (vitamin B6) and ginger in the management of nausea and vomiting in pregnancy
  • one study has shown that ginger reduced symptoms to the same extent as vitamin B6 (4)
• doxylamine succinate-pyridoxine hydrochloride delayed release combination is safe and well tolerated by pregnant women when used in the recommended dose of up to 4 tablets daily in treating nausea and vomiting of pregnancy (5)

Reference:

1. NICE (2008). Antenatal care.
2. Prescriber (2002), 13 (10), 50-68.
3. Ziaei S et al. The efficacy low dose of prednisolone in the treatment of hyperemesis gravidarum. Acta Obstet Gynecol Scand 2004;83:272-5.
4. Smith C et al. A randomized controlled trial of ginger to treat nausea and vomiting in pregnancy. Obset Gynecol 2004;103:639-45.
5. Korean G et al. Maternal safety of the delayed-release doxylamine and pyridoxine combination for nausea and vomiting of pregnancy; a randomized placebo controlled trial. BMC Pregnancy Childbirth. 2015; 15: 59.