What is the recommended post-exposure prophylaxis for a pregnant woman exposed to Hepatitis B (HBV)?

Post-Exposure Prophylaxis for Hepatitis B in Pregnancy

Pregnant women exposed to hepatitis B should receive the same post-exposure prophylaxis as non-pregnant individuals: hepatitis B immune globulin (HBIG) 0.06 mL/kg intramuscularly plus hepatitis B vaccine series initiated simultaneously at a different injection site, with treatment started as soon as possible and ideally within 24 hours of exposure. 1, 2

Immediate Management Based on Exposure Type and Vaccination Status

For Unvaccinated Pregnant Women

Percutaneous or mucosal exposure (needlestick, bite, splash):

• Administer HBIG 0.06 mL/kg IM immediately, preferably within 24 hours (value beyond 7 days unclear) 2
• Initiate hepatitis B vaccine series simultaneously at a different injection site 1
• Standard 3-dose schedule: 0,1, and 6 months 3

Sexual exposure to HBsAg-positive person:

• Give HBIG 0.06 mL/kg as single dose within 14 days of last sexual contact 2
• Start hepatitis B vaccine series concurrently at separate site 2

For Previously Vaccinated Pregnant Women

If antibody status unknown:

• Test exposed person for anti-HBs immediately 1
• If adequate antibody (≥10 mIU/mL): no treatment needed 1
• If inadequate antibody (<10 mIU/mL): give HBIG x1 immediately plus vaccine booster dose 1

If known vaccine non-responder:

• Administer HBIG x1 and initiate revaccination, OR give HBIG x2 (one immediately, second at 1 month) 1

Safety in Pregnancy

Both HBIG and hepatitis B vaccine are safe throughout pregnancy and can be initiated at any gestational age. 1, 4, 5

• A study of 16 pregnant women receiving post-exposure prophylaxis with HBIG and vaccine showed no adverse effects on pregnancy outcomes or offspring 5
• One clinical abortion occurred 2 days after initial immunization but was not attributed to vaccination 5
• Pregnancy testing should be offered to all women of childbearing age before initiating HIV post-exposure prophylaxis, but this does not preclude HBV prophylaxis 1

Important Nuances About Immune Response

Pregnant women may mount a weaker antibody response to hepatitis B vaccine compared to non-pregnant women:

• Peak geometric mean titers were 258 IU/L in pregnant vs. 684 IU/L in non-pregnant women 5
• Seroconversion rates remain similar, but response is slower and lower at all time points 5
• Monitor anti-HBs levels 1-2 months after completing the vaccine series to confirm adequate response (≥10 mIU/mL) 1, 3, 5

Critical Timing Considerations

The efficacy of HBIG decreases dramatically with delayed administration:

• Greatest effectiveness when given as soon as possible after exposure 2
• Should be administered within 24 hours if possible 2
• Value beyond 7 days of exposure is unclear 2
• For sexual exposure, can be given up to 14 days after last contact 2

Administration Details

HBIG and vaccine must be given at different anatomic sites:

• HBIG may be administered at the same time as vaccine without impairing immune response, provided different sites are used 2
• Both should be given intramuscularly 2
• Deltoid muscle preferred for adults 3

Common Pitfalls to Avoid

Do not delay prophylaxis while awaiting source testing:

• If source HBsAg status unknown but high-risk, treat as if source were HBsAg-positive 1
• Initiate vaccine series within 7 days of exposure even if source unavailable for testing 2

Do not confuse post-exposure prophylaxis with antepartum HBIG for chronic HBV carriers:

• Antepartum HBIG administration to chronically infected pregnant women is NOT recommended and does not reduce mother-to-child transmission 1
• This guideline applies only to women already HBsAg-positive, not to post-exposure prophylaxis scenarios 1

Do not withhold treatment due to pregnancy concerns:

• The risk of hepatitis B infection far outweighs any theoretical vaccine risks 5, 6
• Chronic HBV infection acquired perinatally or in early childhood accounts for 50% of chronically infected individuals globally 7

Follow-Up Requirements

Post-vaccination serologic testing:

• Perform anti-HBs testing 1-6 months after completing vaccine series 1, 3
• If anti-HBs <10 mIU/mL, consider revaccination with 1-3 additional doses 1, 3
• 15-25% of non-responders produce adequate antibody after one additional dose; 30-50% after three doses 1, 3

Monitor for acute hepatitis:

• Advise exposed person to seek medical evaluation for any acute illness during follow-up period 1