Nausea and Vomiting of Pregnancy

Nausea is a common symptom in pregnancy, particularly early on. Nausea and vomiting in pregnancy starts in the first trimester, peaking around 8 – 12 weeks gestation. The severe form of nausea and vomiting in pregnancy is called hyperemesis gravidarumHyper- refers to lots, -emesis refers to vomiting and gravida- relates to pregnancy.

Nausea and vomiting are normal during early pregnancy. Symptoms usually start from 4 – 7 weeks, are worst around 10 – 12 weeks and resolve by 16 – 20 weeks. Symptoms can persist throughout pregnancy.

The placenta produces human chorionic gonadotropin (hCG) during pregnancy. This hormone is thought to be responsible for nausea and vomiting. Theoretically, higher levels of hCG result in worse symptoms.

Nausea and vomiting are more severe in molar pregnancies and multiple pregnancies due to the higher hCG levels. It also tends to be worse in the first pregnancy and overweight or obese women.



Nausea and vomiting of pregnancy can be diagnosed based on a typical history. Nausea and vomiting needs to start in the first trimester, and other causes need to be excluded before making a diagnosis.


Hyperemesis Gravidarum

Hyperemesis gravidarum is the severe form of nausea and vomiting in pregnancy. The RCOG guideline (2016) criteria for diagnosing hyperemesis gravidarum are “protracted” NVP plus:

  • More than 5 % weight loss compared with before pregnancy
  • Dehydration
  • Electrolyte imbalance


Assessing the Severity

The severity can be assessed using the Pregnancy-Unique Quantification of Emesis (PUQE) score. This gives a score out of 15:

  • < 7: Mild
  • 7 – 12: Moderate
  • > 12: Severe



Antiemetics are used to suppress nausea. Vaguely in order of preference and known safety, the choices are:

  1. Prochlorperazine (stemetil)
  2. Cyclizine
  3. Ondansetron
  4. Metoclopramide


Ranitidine or omeprazole can be used if acid reflux is a problem.

The RCOG also suggest complementary therapies that may be considered by the woman:

  • Ginger
  • Acupressure on the wrist at the PC6 point (inner wrist) may improve symptoms


Mild cases can be managed with oral antiemetics at home. Admission should be considered when:

  • Unable to tolerate oral antiemetics or keep down any fluids
  • More than 5 % weight loss compared with pre-pregnancy
  • Ketones are present in the urine on a urine dipstick (2 + ketones on the urine dipstick is significant)
  • Other medical conditions need treating that required admission


Moderate-severe cases may require ambulatory care (e.g. early pregnancy assessment unit) or admission for:

  • IV or IM antiemetics
  • IV fluids (normal saline with added potassium chloride)
  • Daily monitoring of U&Es while having IV therapy
  • Thiamine supplementation to prevent deficiency (prevents Wernicke-Korsakoff syndrome)
  • Thromboprophylaxis (TED stocking and low molecular weight heparin) during admission


Last updated August 2020
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