What is the recommended treatment for latent tuberculosis (TB) in pregnant women?

Treatment of Latent Tuberculosis in Pregnant Women

For pregnant women with latent tuberculosis infection (LTBI), isoniazid given daily or twice weekly for 9 months is the recommended treatment regimen. 1

First-Line Treatment Options

Isoniazid (INH) Regimen

• Preferred regimen: 9 months of isoniazid
  • Dosing: 300mg daily for adults or 5mg/kg up to 300mg daily 2
  • Alternative: Twice-weekly dosing (900mg or 15mg/kg) under directly observed therapy (DOT) 1
• Acceptable alternative: 6 months of isoniazid (provides substantial protection but 9 months is preferred) 1
• Pyridoxine (vitamin B6) supplementation: 25mg daily should be given to all pregnant women on isoniazid to prevent peripheral neuropathy 1, 3

Risk Assessment and Treatment Timing

The decision about when to start treatment depends on the woman's risk profile:

High-Risk Pregnant Women

• For women at high risk for progression to active TB (especially HIV-infected or recently infected), treatment should not be delayed due to pregnancy, even during the first trimester 1
• The risk of untreated tuberculosis to both mother and fetus outweighs potential medication risks 1, 3

Lower-Risk Pregnant Women

• For women with lower risk of progression to active TB, some experts recommend waiting until after delivery to start treatment 1

Safety Considerations

• Isoniazid crosses the placental barrier but is not teratogenic 1, 3
• Extensive use during pregnancy has shown no increased risk of birth defects, even when given during the first trimester 1
• Rifampin is likely safe in pregnancy but is generally reserved for specific situations (e.g., isoniazid resistance) 1
• Pyrazinamide is typically avoided during pregnancy in the US due to insufficient teratogenicity data, though it is recommended by WHO in some circumstances 1
• Streptomycin is contraindicated in pregnancy due to risk of congenital deafness 1, 2

Monitoring During Treatment

• Initial clinical evaluation before starting treatment
• Monthly follow-up evaluations for women on isoniazid 1
• Baseline liver function tests are indicated for pregnant women 1
• Ongoing monitoring for hepatotoxicity is essential, as pregnancy does not increase the risk but does complicate management if it occurs 3
• Patient education about side effects and when to stop medication is crucial 1

Special Situations

Isoniazid-Resistant TB Exposure

• For contacts of patients with isoniazid-resistant, rifampin-susceptible TB:
  • Rifampin daily for 4 months is recommended if pyrazinamide cannot be tolerated 1

Breastfeeding Considerations

• Breastfeeding is not contraindicated for mothers on LTBI treatment 1
• The small amounts of isoniazid in breast milk do not cause toxicity in infants 2
• Infants of breastfeeding mothers taking isoniazid should receive supplemental pyridoxine 1
• The amount of medication in breast milk is insufficient for treating LTBI in the infant 2

Common Pitfalls to Avoid

1. Failure to rule out active TB: Always exclude active TB before starting LTBI treatment through history, physical examination, chest radiography, and bacteriologic studies when indicated 1

2. Inadequate monitoring: Pregnancy requires careful clinical and laboratory monitoring for hepatotoxicity, especially with isoniazid 1

3. Stopping treatment prematurely: Completion of therapy is based on total number of doses administered—not duration alone 1

4. Overlooking pyridoxine supplementation: Always provide vitamin B6 to pregnant women on isoniazid 1, 3

5. Poor adherence management: Consider DOT for twice-weekly regimens to improve completion rates 1