Nausea and vomiting in pregnancy
Nausea and vomiting in pregnancy, colloquially morning sickness, classically begins before 9 weeks and resolves by 16 to 20 weeks, and its severe end, hyperemesis gravidarum, causes greater than 5% pre-pregnancy weight loss, dehydration, ketonuria, and electrolyte disturbance. Management steps from diet and pyridoxine-doxylamine through antihistamine and dopamine-antagonist antiemetics to ondansetron, with IV fluids, thiamine before dextrose, electrolyte repletion, and short-course corticosteroids reserved for refractory hyperemesis.
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What this article covers
- Overview
Definition: nausea with or without vomiting that classically begins in the first trimester and can occur at any time of day, not only in the morning, hence its popular name.
- Epidemiology
Very common: affects most pregnancies to some degree, making it one of the most frequent complaints of early pregnancy.
- Risk factors
Multifetal gestation: higher circulating beta-hCG from twin or higher-order pregnancy drives more severe symptoms, including reflux.
- Pathophysiology
Hormonal driver: rising beta-hCG parallels the timing and severity of symptoms, which is why the highest-hCG states, multifetal gestation and molar pregnancy, produce the most severe symptoms.
- Clinical features
Nausea with or without vomiting, classically first trimester: onset before 9 weeks of gestation, occurring at any time of day despite the "morning sickness" label.
- Differential diagnosis
Hyperemesis gravidarum: not a separate cause but the severe end of this spectrum, distinguished by greater than 5% weight loss, ketonuria, and electrolyte disturbance (hyperemesis gravidarum).
- Diagnosis
This is a clinical diagnosis based on the classic history and timing: nausea with or without vomiting beginning before 9 weeks of gestation without abdominal pain or fever; no labs or imaging are…
- Management
Start with dietary and lifestyle measures for intermittent, mild symptoms: avoid triggering foods and smells, eat smaller and more frequent meals, and temporarily hold the prenatal multivitamin…
- Complications
Wernicke encephalopathy: thiamine depletion from prolonged vomiting, precipitated by giving dextrose before thiamine, producing the triad of confusion, ophthalmoplegia, and ataxia; treat any…
- Prognosis
Most cases resolve spontaneously by 16 to 20 weeks with dietary measures alone or with stepwise antiemetic therapy, without lasting sequelae.
- Prevention
Start pyridoxine with or without doxylamine early and proactively in a patient with a prior history of significant nausea and vomiting of pregnancy or hyperemesis gravidarum, rather than waiting for symptoms to become moderate to severe.
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Related articles
- Hyperemesis gravidarum
Hyperemesis gravidarum is severe, persistent first-trimester vomiting causing starvation ketosis and at least a 5% loss of prepregnancy weight, distinguishing it from ordinary nausea and vomiting of pregnancy. Management follows a stepwise antiemetic ladder from doxylamine-pyridoxine through IV fluids, thiamine, and refractory-line corticosteroids.
- Gastroesophageal reflux disease (GERD)
GERD is retrograde reflux of gastric contents into the esophagus causing heartburn and regurgitation, diagnosed clinically and confirmed by response to an empiric PPI trial, with endoscopy reserved for alarm features or refractory symptoms. Management proceeds from lifestyle measures through an 8-week once-daily PPI trial, dose escalation or agent switch for partial response, and fundoplication for medication-refractory or regurgitation-predominant disease.
- Graves disease
Graves disease is an autoimmune disorder in which thyrotropin receptor antibodies stimulate the thyroid, causing hyperthyroidism, and is the most common cause of thyrotoxicosis in iodine-sufficient regions. Diagnosis rests on a suppressed thyroid-stimulating hormone with elevated free thyroxine and positive thyrotropin receptor antibodies, and first-line treatment is a thionamide, most often methimazole, with radioactive iodine or thyroidectomy reserved for recurrence or patient preference.
- Antiemetics
Antiemetics are grouped by the receptor they block along the emetic pathway, and correct use is a matching exercise: identify the trigger (chemotherapy, postoperative, vestibular, gastroparesis, or pregnancy) and select the class built for that pathway, most often a 5-HT3 antagonist, a D2 antagonist, an NK1 antagonist, or an antihistamine/anticholinergic, layered with dexamethasone for chemotherapy-induced disease.
- Refeeding syndrome
Refeeding syndrome is a potentially fatal shift of phosphate, potassium, and magnesium into cells when nutrition is reintroduced too quickly to a malnourished patient, driven by an insulin surge that also causes fluid retention and thiamine depletion. Prevention rests on identifying at-risk patients before feeding, starting calories low, giving thiamine first, and repleting electrolytes proactively rather than reactively.
- Peptic ulcer disease
Peptic ulcer disease is a mucosal break in the stomach or duodenum caused chiefly by Helicobacter pylori infection or NSAID use, diagnosed by upper endoscopy with biopsy of gastric ulcers to exclude malignancy. Treatment eradicates H. pylori when present, stops the ulcerogenic drug, and heals the ulcer with a proton pump inhibitor, while its complications of bleeding, perforation, and obstruction drive most of its morbidity.
- Preeclampsia
New-onset hypertension after 20 weeks of gestation with proteinuria or end-organ dysfunction, driven by abnormal placental spiral artery remodeling and widespread endothelial dysfunction. Eclampsia is preeclampsia complicated by seizures; magnesium sulfate treats and prevents seizures, and prompt delivery is the only definitive cure for both.