What type of immunity does a baby have when he receives antibodies from his mother before birth?

The type of immunity a baby has when receiving antibodies from the mother before birth is known as passive immunity. This occurs when antibodies are transferred from one individual to another, providing temporary protection against pathogens. In this case, the mother's antibodies cross the placenta to the fetus, offering the baby immediate immunity without the baby having to generate its own immune response.

Passive immunity is important for newborns, as their immune systems are still developing and may not yet be fully equipped to fight off infections. This transfer provides crucial protection against diseases during the early stages of life when the baby's own immune system is not fully functional.

Active immunity, in contrast, involves the body producing its own antibodies in response to an infection or vaccination. Innate immunity refers to the body's first line of defense, which includes physical barriers and immune responses that one is born with. Acquired immunity is a broader term that encompasses both active and passive immunity depending on how the body acquires the immune response. Thus, the most accurate term for the immunity gained through maternal antibodies is passive immunity.