Nausea and vomiting affect up to 80% of pregnant women. Symptoms are most common and most severe during the 1st trimester. Nausea and vomiting of pregnancy is commonly called "morning sickness," but nausea, vomiting, or both may occur at any point during the day. Symptoms vary from mild to severe (hyperemesis gravidarum).
Hyperemesis gravidarum 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) are
Nausea and vomiting of pregnancy (most common)
Hyperemesis gravidarum
Occasionally, prenatal vitamin preparations with iron cause nausea. Rarely, severe, persistent vomiting results from a hydatidiform mole.
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, meningitis) 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. Nausea and vomiting of pregnancy (uncomplicated nausea and vomiting) and hyperemesis gravidarum are diagnoses of exclusion.
History
History of present illness should particularly note the following:
Estimated due date (and whether this is based on last menstrual period or ultrasonography)
Any risk factors for obstetric complications and prior testing or complications during the current pregnancy
Onset and duration of vomiting
Exacerbating and relieving factors
Frequency (intermittent or persistent)
Type (eg, bloody, watery, bilious) and amount of emesis
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 herself or 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 or pyelonephritis), and neurologic symptoms such as headache, weakness, focal deficits, and confusion (migraine or central nervous system (CNS) hemorrhage).
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.
Medications 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
Evaluation of patients during pregnancy should include routine prenatal evaluation to assess maternal and fetal status, including
Assessment of maternal vital signs
Abdominal examination for fundal height
Sometimes, pelvic examination
Evaluation of fetal status with fetal heart rate auscultation
Sometimes pelvic ultrasonography (depending on symptoms and gestational age)
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).
Red flags
The following findings are of particular concern:
No fetal motion or heart sounds
Signs of dehydration (eg, orthostatic hypotension, tachycardia)
Abnormal neurologic examination
Fever
Bloody or bilious emesis
Abdominal pain
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).
Vomiting is more likely to be due to pregnancy if
Symptoms begin during the 1st trimester.
Symptoms persist or recur 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 and hydatidiform mole should be considered.
Nonobstetric causes of nausea should be suspected if symptoms
Begin after the 1st trimester
Are accompanied by abdominal pain, diarrhea, or both
Abdominal tenderness may suggest acute abdomen. Meningismus, neurologic abnormalities, or both suggest a neurologic cause.
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 evaluate fetal status and 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).
Treatment
Pregnancy-induced nausea and vomiting is relieved in some patients by drinking or eating frequently (5 or 6 small meals/day) and/or eating only bland foods (eg, crackers, BRAT diet [bananas, rice, applesauce, dry toast]). Eating before getting out of bed in the morning 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.
Certain drugs (see table 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, 2).
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
Key Points
Nausea and 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.
