Nausea and Vomiting of Pregnancy

Nausea and vomiting of pregnancy is persistent nausea with vomiting in early pregnancy that affects daily life but does not meet the criteria for hyperemesis gravidarum. It is related to rising hCG and affects up to 50 to 80 percent of pregnancies. It matters because it can cause dehydration, electrolyte loss and nutritional deficiency, and treatment is safe and effective.

• Risk factors: first pregnancy, multiple pregnancy, molar pregnancy, previous severe nausea, obesity, family history.
• Starts at 4 to 6 weeks, peaks at 9 weeks.
• Usually settles by 16 to 20 weeks.

Women have nausea and vomiting several times a day, food aversion and tiredness, with weight loss of less than 5 percent. Examination shows normal or mildly dry mucous membranes.

• Severity can be scored with the 24 hour pregnancy unique quantification of emesis score.
• Mild symptoms score 6 or below; moderate 7 to 12; severe 13 or above.
• Differential diagnosis: urinary tract infection, gastroenteritis, hepatitis, peptic ulcer, pancreatitis, thyrotoxicosis, molar pregnancy, malaria.
• Complications: dehydration, electrolyte disturbance, hyperemesis gravidarum, Wernicke encephalopathy, depression, weight loss.

The diagnosis is clinical, with tests to exclude other causes and assess severity.

• Weight, pulse, blood pressure, orthostatic change.
• Urine dipstick for ketones and infection.
• Urea, creatinine and electrolytes if vomiting is frequent.
• Ultrasound for dating, multiple pregnancy and molar pregnancy; liver tests, TSH and malaria test if indicated.

The principle is stepwise treatment, starting with diet and vitamin B6 and moving to antiemetics early.

• Supportive: small frequent meals; oral rehydration with sips; avoid triggers; rest; stop iron tablets until nausea settles; take multivitamins at night.
• Pharmacological: pyridoxine 25 mg oral 8-hourly; doxylamine 10 mg with pyridoxine 10 mg, 2 tablets at night then adjust to 4 tablets daily if available; promethazine 12.5 to 25 mg oral 8-hourly (maximum 100 mg daily); metoclopramide 10 mg oral 8-hourly for up to 5 days; ondansetron 4 mg oral 8-hourly if others fail; folic acid 400 micrograms oral daily.
• Procedures: none.
• Special groups: women with prolonged QT interval avoid ondansetron; women with diabetes monitor glucose and avoid ketoacidosis.
• Red flags: inability to keep down fluids for 24 hours, ketonuria 2 plus or more, weight loss above 5 percent, confusion, jaundice, pulse above 100 per minute.
• Follow-up: review at 1 week; weigh at each visit; admit if dehydrated; reassess at 12 and 20 weeks.