Why do antibodies from the mother only provide temporary immunity to the infant

Antibodies from the mother provide only temporary immunity to the infant because this is a form of passive immunity. In passive immunity, the infant receives pre-formed antibodies from the mother rather than producing them itself. These transferred antibodies have a limited lifespan in the infant's body and are gradually broken down and eliminated over time. The infant's own immune system has not been stimulated to create memory cells for these specific pathogens, so once the maternal antibodies are gone, the protection diminishes.