How is vomiting during pregnancy managed?

Management of Vomiting During Pregnancy

Start with dietary modifications and vitamin B6 (pyridoxine) 10-25 mg every 8 hours, adding doxylamine if symptoms persist—this doxylamine-pyridoxine combination is the only FDA-approved therapy and recommended first-line treatment by the American College of Obstetricians and Gynecologists for both mild nausea/vomiting and hyperemesis gravidarum. 1, 2

Initial Assessment and Severity Stratification

Before initiating treatment, assess severity using the Pregnancy-Unique Quantification of Emesis (PUQE) score: mild (≤6), moderate (7-12), and severe (≥13). 1, 2

Key red flags requiring immediate evaluation: 1, 3

• Weight loss ≥5% of pre-pregnancy weight
• Signs of dehydration (elevated hematocrit, increased urine specific gravity)
• Ketonuria on urinalysis
• Inability to maintain oral intake

Check electrolyte panel, liver function tests (40-50% will have elevated AST/ALT), and urinalysis for ketonuria in moderate-to-severe cases. 1, 2

Stepwise Pharmacologic Management Algorithm

First-Line Therapy (Mild to Moderate Symptoms)

Doxylamine-pyridoxine combination is the preferred initial antiemetic, safe throughout pregnancy and breastfeeding. 1, 3 Start with pyridoxine (vitamin B6) 10-25 mg every 8 hours, adding doxylamine 10-20 mg if symptoms persist. 2

Alternative first-line agents include other antihistamines (promethazine, cyclizine) and phenothiazines (prochlorperazine, chlorpromazine), all sharing similar safety profiles. 1

Second-Line Therapy (Moderate to Severe Symptoms)

When first-line antihistamines fail, metoclopramide is the preferred second-line agent due to similar efficacy to promethazine but with less drowsiness, dizziness, dystonia, and fewer treatment discontinuations. 1, 3

Ondansetron should be reserved as second-line therapy and used on a case-by-case basis before 10 weeks gestation due to concerns about congenital heart defects when used in early first trimester, though recent data suggest the risk is low. 1, 3 After 10 weeks, ondansetron can be used more liberally. 1

Important caveat: A meta-analysis of 25 studies found no significant efficacy difference among metoclopramide, ondansetron, and promethazine, so medication selection should be based on safety profile and gestational age rather than efficacy alone. 1, 3

Third-Line Therapy (Severe Refractory Cases)

Methylprednisolone should be reserved as last resort for severe hyperemesis gravidarum that fails other therapies. 1, 3 Dosing protocol: 16 mg IV every 8 hours for up to 3 days, then taper over 2 weeks to lowest effective dose, with maximum duration of 6 weeks. 1

Use with caution before 10 weeks gestation due to slight increased risk of cleft palate. 1, 3

Critical Supportive Measures

Thiamine Supplementation (Essential to Prevent Wernicke's Encephalopathy)

For any patient with prolonged vomiting, start thiamine 100 mg daily orally for minimum 7 days, then 50 mg daily maintenance. 3 If vomiting persists or patient cannot tolerate oral intake, immediately switch to IV thiamine 200-300 mg daily. 1, 3

Pregnancy increases thiamine requirements, and hyperemesis gravidarum rapidly depletes thiamine stores within 7-8 weeks of persistent vomiting—reserves can be completely exhausted after only 20 days of inadequate oral intake. 1

Hydration and Electrolyte Management

Administer IV fluid resuscitation to correct dehydration, which often improves associated liver enzyme abnormalities. 1, 3 Replace electrolytes with particular attention to potassium and magnesium levels. 1, 3

Dextrose saline may be more effective at reducing nausea than normal saline. 4

Dietary Modifications

Recommend small, frequent, bland meals following the BRAT diet (bananas, rice, applesauce, toast), high-protein and low-fat meals, and avoidance of strong odors and specific food triggers. 1, 2

Ginger supplementation (250 mg capsule four times daily) may be considered as adjunctive therapy. 1, 4

When to Escalate Care

Indications for Hospitalization

Hospitalize patients with: 1, 3

• Frequent vomiting (≥5-7 episodes daily) despite maximal antiemetics
• Progressive weight loss ≥5% of pre-pregnancy weight
• Inability to maintain oral intake of 1000 kcal/day for several days
• Persistent ketonuria or electrolyte abnormalities

Advanced Nutritional Support

Consider nasojejunal feeding (preferred over nasogastric due to better tolerance) before escalating to total parenteral nutrition in patients with escalating symptoms despite maximal medical therapy. 1

Enteral feeding should be reserved for patients who have failed to maintain adequate nutrition despite maximal medical therapy, not for those with nausea or food aversions alone. 1

Common Pitfalls to Avoid

Withdraw phenothiazines or metoclopramide immediately if extrapyramidal symptoms develop. 1

Do not use PRN or intermittent dosing in refractory cases—switch to around-the-clock scheduled antiemetic administration for continuous symptom control. 1

Do not continue escalating promethazine doses when side effects emerge—switch to metoclopramide instead. 3

Expected Timeline and Monitoring

Symptoms typically peak at 8-12 weeks gestation and resolve by week 16 in >50% of patients and by week 20 in 80%, though 10% may experience symptoms throughout pregnancy. 1, 3

Regular monitoring should include: 1, 3

• Serial PUQE scores to track symptom trajectory
• Hydration status and electrolyte balance
• Weight trends
• Fetal growth monitoring (monthly scans from viability in severe cases)

Multidisciplinary Management for Severe Cases

Severe refractory hyperemesis gravidarum requires involvement of obstetricians, gastroenterologists, nutritionists, and mental health professionals, preferably managed at tertiary care centers with multidisciplinary teams experienced in high-risk pregnancies. 1, 3

Mental health support is important as anxiety and depression are common with severe hyperemesis gravidarum. 1

Prognosis and Counseling

Early intervention is crucial to prevent progression from mild nausea and vomiting to hyperemesis gravidarum. 1, 2 Untreated hyperemesis gravidarum is associated with low birth weight, small for gestational age infants, and premature delivery. 1

Recurrence risk in subsequent pregnancies is 40-92%, so counsel patients accordingly. 1, 3