What are the causes and treatments of itching in pregnancy?

Itching in Pregnancy: Causes and Treatment

For pregnant women with itching, immediately evaluate for intrahepatic cholestasis of pregnancy (ICP) by measuring serum bile acids and liver transaminases, as this condition carries significant risk of stillbirth and requires specific management with ursodeoxycholic acid and timed delivery. 1

Differential Diagnosis

Most Common Causes

Pruritus affects approximately 23% of all pregnancies, with most cases having no underlying pathologic process. 1 When pathologic causes exist, consider:

Pregnancy-Specific Dermatoses (with rash):

• Atopic eruption of pregnancy (AEP) - most common pruritic disorder, presents with eczematous rash on face, eyelids, neck, antecubital/popliteal fossae, trunk, and extremities 1
• Polymorphic eruption of pregnancy (PEP) - most common dermatosis overall, characterized by pruritic urticarial papules and plaques on abdomen and proximal thighs 1
• Pemphigoid gestationis (PG) - rare, associated with vesicles and bullae 1

Intrahepatic Cholestasis of Pregnancy (without rash):

• Generalized itching predominantly affecting palms and soles 1
• Worse at night 1
• Generally not associated with rash (though excoriations from scratching may develop) 1
• Occurs in second and third trimesters 1

Other Systemic Causes (without rash):

• Chronic renal failure, thyroid disorders (hypo- or hyperthyroidism), liver disease, malabsorption, parasitosis, HIV, hematologic malignancies, drug reactions (hydrochlorothiazide, opioids), psychiatric conditions 1

Diagnostic Evaluation

History and Physical Examination

Key historical elements to assess: 1

• Onset, extent, severity, timing (worse at night suggests ICP)
• Presence or absence of rash
• Medications (especially narcotics)
• Medical/family history of atopy
• Risk factors for hepatitis or HIV
• Previous history of ICP in prior pregnancies
• Recent weight changes, jaundice, dark urine

Physical examination findings: 1

• ICP: typically no rash except excoriations from scratching
• Dark urine and jaundice are uncommon with ICP and suggest other hepatic diseases
• Assess for specific rash patterns to identify pregnancy-specific dermatoses

Laboratory Testing

For suspected ICP, measure: 1

• Serum bile acid levels (GRADE 1B recommendation)
• Liver transaminases (GRADE 1B recommendation)

Additional workup if other causes suspected: 1

• Complete blood count with differential
• Renal function tests
• Thyroid function (only if clinical features suggest thyroid disease)
• Hepatitis screening if risk factors present

Treatment Approach

For Intrahepatic Cholestasis of Pregnancy

First-line pharmacologic treatment:

• Ursodeoxycholic acid (UDCA) is the first-line agent for maternal symptom relief (GRADE 1A recommendation) 1
• UDCA is safe in pregnancy and lactation 1

Additional symptomatic management for refractory pruritus: 1

• Cholestyramine (4-16 g daily in divided doses, separated from other medications by at least 2 hours)
• Rifampin (300-600 mg daily)
• S-adenosyl-L-methionine (SAMe) (1,000-1,200 mg daily)
• Antihistamines (though evidence is low)

Critical monitoring and delivery timing:

• Begin antenatal fetal surveillance when delivery would be performed for abnormal testing or at diagnosis if later in gestation (GRADE 2C) 1
• For bile acids ≥100 μmol/L: deliver at 36 0/7 weeks due to substantially increased stillbirth risk (GRADE 1B) 1
• For bile acids <100 μmol/L: deliver between 36 0/7 and 39 0/7 weeks (GRADE 1C) 1
• Administer antenatal corticosteroids if delivering before 37 0/7 weeks (GRADE 1A) 1
• Do NOT deliver preterm without laboratory confirmation of elevated bile acids (GRADE 1B) 1

Important caveat for cholestyramine use:

• May exacerbate vitamin K deficiency in cholestatic patients 1
• Monitor PT during pregnancy 1
• Correct vitamin K deficiency if present 1

For Other Pregnancy-Related Pruritus

Non-pharmacologic measures (first-line for all causes): 2

• Use emollients to prevent skin dryness
• Avoid hot baths or showers
• Apply cooling gels
• Keep nails shortened

Pharmacologic options when necessary: 3

• Topical corticosteroids for localized pruritus
• Emollients and topical antipruritics
• Systemic corticosteroids for severe cases
• Antihistamines (limited options in pregnancy)

Antihistamine selection in pregnancy: 2

• Chlorphenamine is often chosen due to long safety record
• Cetirizine is FDA Pregnancy Category B (no evidence of fetal harm, though human studies limited)
• Best to avoid all antihistamines in first trimester when possible
• Use lowest effective dose if deemed necessary

Critical Pitfalls to Avoid

• Never delay delivery in confirmed ICP with bile acids ≥100 μmol/L beyond 36 weeks - stillbirth risk increases substantially 1
• Do not perform preterm delivery based on clinical suspicion alone without laboratory confirmation of elevated bile acids 1
• Do not miss vitamin K deficiency in patients on cholestyramine - monitor PT regularly 1
• Do not assume all itching is benign - 23% of pregnancies have pruritus, but pathologic causes require specific management 1
• Do not forget to separate cholestyramine from other medications by at least 2 hours to avoid interference with absorption 1