What is the age for the stage 'conception' in childhood life?

The stage of conception marks the beginning of human life and occurs when a sperm fertilizes an egg, leading to the formation of a zygote. This process typically happens around two weeks after a woman's last menstrual period, but the actual age of the developing embryo is considered to start at conception. This stage is crucial as it sets the foundation for pregnancy and subsequent development throughout the gestational period.