ScienceContemporaryglobalhigh confidence

Up to 50% of hepatitis B cases are attributed to perinatal transmission from mother to infant, which can occur at or around birth.

Notes on verification

Confirmed by multiple independent peer-reviewed and clinical sources (AJOG, StatPearls/NCBI, PMC reviews), with estimates ranging 35-50%+ depending on region, consistent with the claim's 'up to 50%' framing. [tier=silver indep_score=0.925 clusters=2 claim_tier=notable]

Sources