Nausea & vomiting in pregnancy (NVP), commonly known as "morning sickness", affects 50-90% of pregnant women.
In most women, the condition manifests between the 4th-7th week after last menstrual period and resolves by the 16th week of gestation.
It manifests in a spectrum of severity from mild nausea to very rare life-threatening symptoms.
The etiology is multifactorial.
The pregnant woman's sense of well-being and her daily activities are greatly affected by nausea and vomiting; the physical and emotional impact often leads to anxiety and worry about the effect of the symptoms on the fetus and reduced job efficiency.

Nausea%20-and-%20vomiting%20in%20pregnancy Treatment


Pyridoxine with or without Doxylamine

  • Pyridoxine can be used as monotherapy or in combination with Doxylamine
  • Doxylamine/Pyridoxine combination is considered as the 1st-line of treatment based on evidence supporting its efficacy and safety
    • Improves mild to moderate nausea but does not significantly decrease vomiting
  • Doxylamine is an H1 receptor antagonist that has been shown to be effective for nausea and vomiting in pregnancy (NVP)
  • Pyridoxine is a co-enzyme in the transamination of amino acids and plays an important role in protein metabolism
    • Pyridoxine’s mode of action in alleviating NVP is not known; no clear association has been found between pyridoxine status and NVP
  • Pyridoxine has no known teratogenic effects and is less likely to cause adverse effects than antihistamine antiemetics; but evidence for its benefit in nausea and vomitng (N/V) in early pregnancy remains limited
    • Maximum dose is 200 mg/day in pregnant women but doses of up to 500 mg/day appear to be safe


  • Diphenhydramine, Dimenhydrinate, Hydroxyzine, Meclizine, Promethazine and Trimethobenzamide have been used to control NVP and have been shown to be more effective than placebo
  • Directly inhibit the action of histamine at H1 receptor and indirectly affect the vestibular system, thereby decreasing the stimulation of vomiting center; also promotes antiemetic action by inhibiting muscarinic receptors
  • When used in therapeutic doses, these agents do not appear to be associated with an increased risk of congenital abnormalities


  • Phenothiazines (eg, Chlorpromazine, Prochlorperazine) have demonstrated significant therapeutic effect for severe NVP
    • Chlorpromazine may be given in refractory cases
  • Block postsynaptic mesolimbic dopamine receptors and depress the reticular activating system, thus affecting emesis
  • Studies of pregnant women exposed to various phenothiazines have failed to demonstrate an increased risk of fetal malformation

Propulsive Agent

  • Metoclopramide is a stimulant of upper gastrointestinal tract (GIT) motility
  • Increases lower esophageal sphincter tone and decreases transit time through the upper GIT, also blocks dopamine receptors at the chemoreceptor trigger zone of central nervous system (CNS)
  • NVP is associated with gastric dysrhythmia and the use of motility agents is a common practice
  • Effective and safe but used as 2nd-line agent due to risk of extrapyramidal effects
  • Studies have confirmed the lack of association between Metoclopramide exposure during the 1st trimester and congenital malformation

Other Agents Considered for Refractory Cases 


  • Eg Methylprednisolone (dose 15-20 mg IV 8 hourly)
  • Rationale for use is based on the theory that NVP is partly due to corticotropin deficiency
  • Only a few studies have shown some effectiveness in treating NVP
    • Reserved for treatment of refractory NVP or hyperemesis gravidarum
  • A small but significantly increased risk of oral clefting was noted with 1st trimester exposure
    • Routine use during 1st trimester is not recommended

Serotonin (5-HT3) Antagonist

  • Ondansetron, a 5-HT3 antagonist, has been tried for the treatment of hyperemesis gravidarum (dose 8 mg IV 12 hourly or 1 mg/hour continuously 24 hourly)
  • Evidence on its safety and efficacy for NVP remains limited
  • Use may be considered in women with refractory NVP or hyperemesis gravidarum if other interventions have failed and preferably after the first trimester

Adjunctive Therapy

Acid-suppressive Therapy

  • A study revealed that women with heartburn or acid reflux and NVP experienced significant improvement in symptoms after treatment with acid-reducing agents (eg antacids, H2-receptor antagonists, proton pump inhibitors) and anti-emetics

Non-Pharmacological Therapy

Acupuncture and Acupressure

  • Traditional Chinese medicine belief that stimulation of P6 acupressure point (Neiguan point) can relieve nausea
    • The point is located 3 fingerbreadths above the wrist on the volar surface
  • Data on the benefit of acupressure are equivocal


  • Used in teas, preserves, ginger ale and pill form
  • May be used in mild to moderate nausea and vomiting in pregnancy
  • Has been demonstrated to be more effective than placebo in improving nausea but did not significantly reduce emesis
  • Safety data is lacking though many cultures use ginger as a spice with amounts similar to commonly prescribed therapy (125-250 mg orally 3-4x daily)
Digital Edition
Asia's trusted medical magazine for healthcare professionals. Get your MIMS JPOG - Malaysia digital copy today!
Sign In To Download
Editor's Recommendations
Most Read Articles
Elaine Soliven, 22 Feb 2021
Older maternal age and higher body mass index (BMI) were associated with an increased risk of nulliparous, term, singleton, vertex (NTSV) Caesarean delivery, according to a study presented at SMFM 2021.