Nausea and vomiting affect up to 80% of pregnant women. Symptoms are most common and most severe during the 1st trimester. Although common usage refers to morning sickness, nausea, vomiting, or both typically may occur at any point during the day. Symptoms vary from mild to severe (hyperemesis gravidarum).
Hyperemesis gravidarum Hyperemesis Gravidarum Hyperemesis gravidarum is severe nausea and vomiting during pregnancy that results in dehydration, weight loss, and ketosis. Diagnosis is clinical and by measurement of urine ketones, serum... read more is persistent, severe pregnancy-induced vomiting that causes significant dehydration, often with electrolyte abnormalities, ketosis, and weight loss.
Pathophysiology
The pathophysiology of nausea and vomiting during early pregnancy is unknown, although metabolic, endocrine, gastrointestinal, and psychologic factors probably all play a role. Estrogen may contribute because estrogen levels are elevated in patients with hyperemesis gravidarum.
Etiology
The most common causes of uncomplicated nausea and vomiting during early pregnancy (see table Some Causes of Nausea and Vomiting During Early Pregnancy Some Causes of Myoclonus 
) are
Morning sickness (most common)
Hyperemesis gravidarum
Occasionally, prenatal vitamin preparations with iron cause nausea. Rarely, severe, persistent vomiting results from a hydatidiform mole Gestational Trophoblastic Disease Gestational trophoblastic disease is proliferation of trophoblastic tissue in pregnant or recently pregnant women. Manifestations may include excessive uterine enlargement, vomiting, vaginal... read more 
.
Vomiting can also result from many nonobstetric disorders. Common causes of acute abdomen (eg, appendicitis, cholecystitis) may occur during pregnancy and may be accompanied by vomiting, but the chief complaint is typically pain rather than vomiting. Similarly, some central nervous system (CNS) disorders (eg, migraine, CNS hemorrhage, increased intracranial pressure) may be accompanied by vomiting, but headache or other neurologic symptoms are typically the chief complaint.
Evaluation
Evaluation of patients with nausea and vomiting during early pregnancy aims to exclude serious or life-threatening causes of nausea and vomiting. Morning sickness (uncomplicated nausea and vomiting) and hyperemesis gravidarum are diagnoses of exclusion.
History
History of present illness should particularly note the following:
Onset and duration of vomiting
Exacerbating and relieving factors
Type (eg, bloody, watery, bilious) and amount of emesis
Frequency (intermittent or persistent)
Important associated symptoms include diarrhea, constipation, and abdominal pain. If pain is present, the location, radiation, and severity should be queried. The examiner should also ask what social effects the symptoms have had on the patient and her family (eg, whether she is able to work or to care for her children).
Review of systems should seek symptoms of nonobstetric causes of nausea and vomiting, including fever or chills, particularly if accompanied by flank pain or voiding symptoms (urinary tract infection Introduction to Urinary Tract Infections (UTIs) Urinary tract infections (UTIs) can be divided into upper tract infections, which involve the kidneys ( pyelonephritis), and lower tract infections, which involve the bladder ( cystitis), urethra... read more or pyelonephritis), and neurologic symptoms such as headache, weakness, focal deficits, and confusion (migraine Migraine Migraine is an episodic primary headache disorder. Symptoms typically last 4 to 72 hours and may be severe. Pain is often unilateral, throbbing, worse with exertion, and accompanied by symptoms... read more or CNS hemorrhage Intracerebral Hemorrhage Intracerebral hemorrhage is focal bleeding from a blood vessel in the brain parenchyma. The cause is usually hypertension. Typical symptoms include focal neurologic deficits, often with abrupt... read more 
).
Past medical history includes questions about morning sickness or hyperemesis in past pregnancies. Past surgical history should include questions about any prior abdominal surgery, which would predispose a patient to mechanical bowel obstruction.
Drugs taken by the patient are reviewed for drugs that could contribute (eg, iron-containing compounds, hormonal therapy) and for safety of these drugs taken during pregnancy.
Physical examination
Examination begins with review of vital signs for fever, tachycardia, and abnormal blood pressure (too low or too high).
A general assessment is done to look for signs of toxicity (eg, lethargy, confusion, agitation). A complete physical examination, including pelvic examination, is done to check for findings suggesting serious or potentially life-threatening causes of nausea and vomiting (see table Relevant Physical Examination Finding in a Pregnant Patient With Vomiting Relevant Physical Examination Findings in a Pregnant Patient With Vomiting ).
Red flags
The following findings are of particular concern:
Abdominal pain
Signs of dehydration (eg, orthostatic hypotension, tachycardia)
Fever
Bloody or bilious emesis
No fetal motion or heart sounds
Abnormal neurologic examination
Persistent or worsening symptoms
Interpretation of findings
Distinguishing pregnancy-related vomiting from vomiting due to other causes is important. Clinical manifestations help (see table Some Causes of Nausea and Vomiting During Early Pregnancy Some Causes of Myoclonus ).
Vomiting is less likely to be due to pregnancy if it
Begins after the 1st trimester
Is accompanied by abdominal pain, diarrhea, or both
Abdominal tenderness may suggest acute abdomen. Meningismus, neurologic abnormalities, or both suggest a neurologic cause.
Vomiting is more likely to be due to pregnancy if
It begins during the 1st trimester.
It lasts or recurs over several days to weeks.
Abdominal pain is absent.
There are no symptoms or signs involving other organ systems.
If vomiting appears to be pregnancy-related and is severe (ie, frequent, prolonged, accompanied by dehydration), hyperemesis gravidarum Hyperemesis Gravidarum Hyperemesis gravidarum is severe nausea and vomiting during pregnancy that results in dehydration, weight loss, and ketosis. Diagnosis is clinical and by measurement of urine ketones, serum... read more and hydatidiform mole Gestational Trophoblastic Disease Gestational trophoblastic disease is proliferation of trophoblastic tissue in pregnant or recently pregnant women. Manifestations may include excessive uterine enlargement, vomiting, vaginal... read more should be considered.
Testing
Patients with significant vomiting, signs of dehydration, or both usually require testing. If hyperemesis gravidarum is suspected, urine ketones are measured; if symptoms are particularly severe or persistent, serum electrolytes are measured. If fetal heart sounds are not clearly audible or detected by fetal Doppler, pelvic ultrasonography should be done to rule out hydatidiform mole.
Other tests are done based on clinically suspected nonobstetric disorders (see table Some Causes of Nausea and Vomiting During Early Pregnancy Some Causes of Myoclonus ).
Treatment
Pregnancy-induced vomiting may be relieved by drinking or eating frequently (5 or 6 small meals/day), but only bland foods (eg, crackers, soft drinks, BRAT diet [bananas, rice, applesauce, dry toast]) should be eaten. Eating before rising may help.
If dehydration (eg, due to hyperemesis gravidarum) is suspected, 1 to 2 L of normal saline or Ringer’s lactate is given IV, and any identified electrolyte abnormalities are corrected.
After initial fluid resuscitation, dextrose IV may be added to maintenance fluid if oral intake remains limited. Before administration of dextrose, thiamin 100 mg IV should be given to prevent Wernicke encephalopathy.
Certain drugs (see table Suggested Drugs for Nausea and Vomiting During Early Pregnancy Suggested Drugs for Nausea and Vomiting During Early Pregnancy ) can be used to relieve nausea and vomiting during the 1st trimester without evidence of adverse effects on the fetus.
Rarely, weight loss continues and symptoms persist despite treatment. In such cases, enteral nutrition via a nasogastric or nasoduodenal tube may be considered. Peripherally inserted central catheters are associated with a high rate of infection and thromboembolism in pregnancy and should be avoided (1 Treatment references Nausea and vomiting affect up to 80% of pregnant women. Symptoms are most common and most severe during the 1st trimester. Although common usage refers to morning sickness, nausea, vomiting... read more , 2 Treatment references Nausea and vomiting affect up to 80% of pregnant women. Symptoms are most common and most severe during the 1st trimester. Although common usage refers to morning sickness, nausea, vomiting... read more ).
Vitamin B6 is used as monotherapy; other drugs are added if symptoms are not relieved. Extended-release doxylamine plus pyridoxine can be given to women who do not respond to initial therapy.
Ginger (eg, ginger capsules 250 mg orally 3 or 4 times a day, ginger lollipops), acupuncture, motion sickness bands, and hypnosis may help, as may switching from prenatal vitamins to a children’s chewable vitamin with folate.
Treatment references
1. Holmgren C, M Aagaard-Tillery KM, Silver RM, et al: Hyperemesis in pregnancy: An evaluation of treatment strategies with maternal and neonatal outcomes. Am J Obstet Gynecol 198 (1):56.e1–4, 2008. doi: 10.1016/j.ajog.2007.06.004
2. Cape AV, Mogensen KM, Robinson MK, Carusi DA: Peripherally inserted central catheter (PICC) complications during pregnancy. JPEN J Parenter Enteral Nutr 38 (5):595–601, 2014. doi: 10.1177/0148607113489994 Epub 2013 May 28. PMID: 23715775.
Key Points
Vomiting during pregnancy is usually self-limited and responds to dietary modification.
Hyperemesis gravidarum is less common but is severe, leading to dehydration, ketosis, and weight loss.
Consider nonobstetric causes of nausea and vomiting.
