Vomiting in Pregnancy

last authored: Jan 2011, Danielle Maurice
last reviewed: Jan 2011, David LaPierre





Nausea and vomiting in pregnancy (colloquially known as "morning sickness") are common complaints. The American College of Obstetricians and Gynecologists practice guidelines state that 70% to 85%  of pregnant women experience nausea and vomiting at some point during the pregnancy (ACOG, 2004).


It is most common during the 1st trimester of pregnancy and usually disappears by the 14th week of pregnancy. It is important to determine the etiology of the patient's vomiting, taking into account the frequency, severity, and onset (e.g. presentations of vomiting later along in the pregnancy) and associated symptoms to create a differential diagnosis.


N/V in pregnancy can have a significant impact on jobs, activities, family relationships, and moods.


Hyperemesis gravidarum is nausea and vomiting severe enough to cause physiological and biochemical effects, including significant dehydration, often with electrolyte abnormalities, ketosis, and weight loss. It usually occurs during the first trimester of ~1% of all pregnancies and then decreases, but is present throughout pregnancy in a few women.



The Case of...

A 22-year old pregnant women comes to your family practice complaining of nausea and vomiting for the past week with increasing severity. She is 6 weeks pregnant and this is her first pregnancy.

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Causes and Risk Factors

Causes of nausea and vomiting in pregnancy include:

Risk factors include:

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The pathophysiology remains unclear, however, the cause of nausea and vomiting in pregnancy is thought to be related to the high levels of beta-hCG and estrogen, as well as other hormonal, immunologic, and psychological contributors.

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Signs and Symptoms

  • history
  • physical exam


It is important to take a complete history, as morning sickness or hyperemesis are diagnoses of exclusion.


Ask about intake patterns to determine if any offending foods may be identified.


History of present illness:

  • onset and duration of vomiting
  • aggravating/alleviating factors
  • type (eg, bloody, watery, bilious), volume, and frequency of vomit

Important associated symptoms include:

  • diarrhea
  • constipation
  • abdominal pain (location, radiation, and severity)

Review of systems should seek symptoms of nonobstetric causes of nausea and vomiting, including

  • dysuria, flank pain, fever or chills (UTI or pyelonephritis)
  • neurologic symptoms: headache, weakness, confusion (migraine or CNS hemorrhage).

Past medical/surgical history:

  • morning sickness or hyperemesis in past pregnancies.
  • abdominal surgery (mechanical bowel obstruction)


  • drugs that could contribute (eg, iron-containing compounds, hormonal therapy)
  • drugs that may not be saf during pregnancy

Social history:

  • can she care for herself, her family, and work?

Physical Exam

Physical exam findings that may be found, according to various causes of vomiting in pregnancy, include:

general assessment

  • dehydation
  • weight loss
  • lethargy, confusion, agitation

vital signs

  • fever
  • tachycardia
  • hyper/hypotension

head and neck

  • dry mucosa
  • icterus
  • neck stiffness (meningismus)



  • absent or high-pitched tinkling bowel sounds
  • focal tenderness
  • peritoneal signs (guarding, rigidity, rebound)


  • flank tenderness to percussion
  • uterus too large for dates
  • absent fetal heart sounds
  • grapelike tissue from cervix


  • confusion
  • photophobia
  • focal weakness
  • nystagmus

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  • lab investigations
  • diagnostic imaging

Lab Investigations

Important investigations for serious vomiting include:

  • electrolytes
  • urine ketones

Given other items on the differential, it is reasonable to consider:

  • CBC
  • BUN, creatinine
  • thyroid function
  • liver enzymes, bilirubin
  • amylase
  • urinalysis
  • acid-base disturbances



Diagnostic Imaging

A fetal doppler should be used to ascertain fetal viability. If it is not able to be located, ultrasound surveillance is warranted to rule out hyadifirom mole.

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Differential Diagnosis

It is important to consider and exclude other causes of nausea and vomiting, including:

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It is important to also treat heartburn, depression, and anxiety.

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Consequences and Course

Nausea and vomiting in pregnancy is generally mild and self-limiting.


According to one study, mean gestational age of onset approximately 6 weeks and with peak severity at weeks 11 to 13. Almost 50% of cases resolve by week 14 gestation, and 90% by week 22 (Lacroix, Ealson, and Melzack, 2000).


A prospective study of 575 women having live singleton births and 75 having spontaneous abortions found a decreased risk for spontaneous abortions in women having nausea during that pregnancy (3)


Maternal consequences include:

Fetal consequences are rare, but include IUGR.

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Resources and References

Merck Manuals, 'Nausea and Vomiting During Early Pregnancy'


American College of Obstetricians and Gynecologists (ACOG). Nausea and vomiting of pregnancy. Washington (DC): American College of Obstetricians and Gynecologists (ACOG); 2004 Apr. 13 p. (ACOG practice bulletin; no. 52).


Lacroix R, Eason E, Melzack R. 2000. Nausea and vomiting during pregnancy: A prospective study of its frequency, intensity, and patterns of change. Am J Obstet Gynecol. 182(4):931-7.


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Topic Development

authors: Sophie Maurice

reviewers: David LaPierre


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