maternal antibody decay
The gradual decline of protective antibodies transferred from mother to infant through placenta and breast milk, typically occurring over 6-12 months.
Full Definition
Maternal antibody decay describes the natural waning of passive immunity in infants as maternally-derived antibodies are metabolized and eliminated. These antibodies, primarily IgG, cross the placenta during pregnancy and provide temporary protection against infections the mother has encountered. The half-life of maternal IgG is approximately 3-4 weeks in healthy infants, with most maternal antibodies disappearing by 6-12 months of age. Understanding this timeline is crucial for interpreting serologic tests in infants and timing vaccinations appropriately.
Usage
Usage note: Do not confuse with primary immunodeficiency when evaluating low antibody levels in infants.
In Context
- "The declining antibody titers reflected normal maternal antibody decay rather than vaccine failure." — Vaccination response assessment
- "Maternal antibody decay was complete by 10 months, allowing for accurate serologic testing." — Immunology follow-up report