What is the management approach for vomiting in pregnancy?

Management of Vomiting in Pregnancy

Start with dietary modifications and lifestyle changes, then escalate to vitamin B6 (pyridoxine) 10-25 mg every 8 hours, followed by adding doxylamine if symptoms persist, with further escalation to metoclopramide or ondansetron for severe cases or hyperemesis gravidarum. 1, 2, 3

Initial Non-Pharmacological Management

Begin with conservative measures that are effective for mild nausea and vomiting of pregnancy (NVP), which affects 30-90% of pregnant women 3:

• Eat small, frequent, bland meals including the BRAT diet (bananas, rice, applesauce, toast) 1, 3
• Consume high-protein, low-fat meals while avoiding spicy, fatty, acidic, and fried foods 1, 3
• Identify and avoid specific triggers such as foods with strong odors or certain activities 1, 3
• Separate solid and liquid intake to reduce gastric distension 3

First-Line Pharmacological Treatment

When dietary modifications fail to control symptoms, escalate to pharmacological therapy:

Vitamin B6 (Pyridoxine)

• Dose: 10-25 mg every 8 hours (total daily dose 30-75 mg divided into three doses), as recommended by ACOG 1, 2
• This dosing stays well below the upper tolerable limit of 100 mg/day for adults 2
• Early treatment is critical to prevent progression to hyperemesis gravidarum 2

Ginger

• Dose: 250 mg capsule four times daily as an alternative or adjunct to vitamin B6 1, 3

Second-Line Pharmacological Treatment

For persistent symptoms despite vitamin B6:

Doxylamine (H1-Receptor Antagonist)

• FDA-approved and recommended by ACOG for persistent NVP refractory to non-pharmacologic therapy 1
• Available in combination with pyridoxine in 10 mg/10 mg and 20 mg/20 mg formulations 1, 3
• Doxylamine, promethazine, and dimenhydrinate are considered safe first-line antiemetic therapies 1

Third-Line Treatment for Moderate to Severe NVP

Metoclopramide

• Can be used as second-line therapy for moderate to severe NVP 1, 3
• In randomized studies comparing promethazine and metoclopramide, both demonstrated efficacy 1

Ondansetron

• Can be used as second-line therapy for moderate to severe NVP 3
• FDA-approved for chemotherapy-induced and postoperative nausea/vomiting, with established safety profile 4

Management of Hyperemesis Gravidarum (HG)

HG is the severe form affecting 0.3-2% of pregnancies, characterized by intractable vomiting, dehydration, weight loss >5% of prepregnancy weight, and electrolyte imbalances 1, 3:

Evaluation

• Assess for signs of dehydration: orthostatic hypotension, decreased skin turgor, dry mucus membranes 1
• Check for malnutrition: weight loss and muscle wasting 1
• Perform neurologic evaluation for neuropathy or vitamin deficiency 1
• Laboratory evaluation: assess extent of dehydration, nutritional/vitamin deficiencies, and electrolyte imbalances (elevated liver enzymes occur in 40-50% of HG patients) 1
• Ultrasonography to detect multiple or molar pregnancies, assess fetal growth, and rule out hepatobiliary, vascular, or renal causes 1

Treatment

• Hospitalization with intravenous hydration and electrolyte replacement 3
• Thiamine (vitamin B1) supplementation: 100 mg daily for minimum 7 days, followed by maintenance dose of 50 mg daily until adequate oral intake is established, to prevent Wernicke encephalopathy and refeeding syndrome 1, 3
• Continue vitamin B6 (pyridoxine) as first-line treatment for mild cases 1
• Escalate to more aggressive antiemetic therapy including metoclopramide, ondansetron, promethazine, or intravenous glucocorticoids for refractory cases 1, 2
• Nutritional support as needed 3

Critical Pitfalls to Avoid

• Do not delay treatment: Early intervention prevents progression from NVP to HG, which can lead to serious complications including Wernicke's encephalopathy, central pontine myelinolysis, and maternal death if inadequately treated 2, 5
• Do not exceed vitamin B6 upper limit: Doses at or above 100 mg/day approach the upper tolerable limit and may cause peripheral neuropathy 2
• Monitor for progressive ileus or gastric distension: Particularly in patients receiving antiemetics after abdominal surgery or with chemotherapy-induced nausea 4
• For patients with history of bariatric surgery: Deflate adjustable gastric bands to prevent band slippage and nutrient deficiencies 3