Nausea and Vomiting of Pregnancy (NVP)

Contributor: Francis Nuthalapaty, MD
Last Update: 2/1/2016

Background:
Overall 70% – 85% of pregnant women experience some form of NVP.  Hyperemesis gravidarum (HG) is the most severe form of NVP and is characterized by persistent vomiting, weight loss exceeding 5% of prepregnancy weight, and ketonuria.  HG occurs in 0.5% to 1% of all pregnancies.  Biochemical hyperthyroidism is associated with NVP due to the action of human chorionic gonadotropin (HCG) on the thyroid-stimulating hormone (TSH) receptor.  Hyperthyroidism does not cause NVP and routine thyroid function tests are not indicated.

Clinical Course:
The mean gestational age at onset is 5 – 6 weeks from the last menstrual period.  Severity and frequency of symptoms peak at ~9 weeks and then begin to subside.  Symptoms persist beyond 16 weeks in only ~10% to 15% of women.  When NVP persists in the second and third trimesters, the intensity remains fairly stable and generally does not lessen.

Diagnostic Approach:

It is emphasized that NVP is a diagnosis of exclusion.  Physical exam findings which are not characteristic of NVP include:

Abdominal pain
Abdominal tenderness
Pain that precedes or is out of proportion to the NV suggestive of an intraabdominal or retroperitoneal etiology
Fever
Headache
Abnormal neurologic examination (suggestive of a primary neurological disorder)
Goiter (suggestive of primary thyroid disease)

The presence of these findings should lead to consideration of other serious medical conditions such as pyelonephritis and appendicitis.
An ultrasound evaluation should be performed (if not done already) to rule out predisposing factors such as multiple gestation or molar pregnancy.

Classification
After a thorough evaluation, patients with NVP can be classified according to the following criteria:

Management Approach 
If symptoms of NVP are present and impacting the daily functioning of the affected woman, some form of management should be initiated in order to prevent progression to HG.  Medications should be administered on a scheduled basis with doses titrated to the individual patient needs.  Patients who develop severe NVP or HG require urgent medical care due to dehydration and malnutrition.

Nausea and Vomiting of Pregnancy: Outpatient Treatment Algorithm

*Dietary/Lifestyle Modifications:

• Eating frequently in small amounts
• Eating high-carbohydrate, low-fat foods
• Eating protein-predominant meals
• Eating a bland, dry diet
• Drinking small amounts of cold, clear, carbonated or sour liquids
• Drinking between meals rather than with meals
• Lying down as needed; getting plenty of rest
• Changing position slowly, especially when rising
• Going outside for fresh air as needed
• Avoiding offensive foods and smells
• Not brushing teeth after eating

** In the US doxylamine is available as the active ingredient in Unisom Sleep Tabs, one half a scored 25 mg tablet can be used to provide 12.5 mg dose of doxylamine.

Inpatient Triage Referral Criteria:
Dehydration
Ketonuria
Intractable vomiting
Significant weight loss

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References

1. Herbert WNP, Goodwin, TM, Koren G, Phelan, S: Nausea and Vomiting of Pregnancy.  APGO Educational Series on Women’s Health Issues. April 2001.