How does passive immunity develop naturally?

Passive immunity:

1. It is developed by the introduction of antibodies into our bodies.
2. It can provide immediate relief since directly antibodies are introduced into the body.
3. It does not persist for a long time.
4. Example: Antibodies for fighting tetanus and diphtheria.
5. It can be of two types based on the sources of antibodies- natural and artificial.
6. Natural passive immunity is developed before birth due to the introduction of the mother's antibodies into the foetal body.

So, natural passive immunity develops when the antibodies from the mother enter the body of the foetus during the foetal development inside the womb of the mother.