Stage I: PreIndustrial Stage: Rural countries have high birth and high but fluctuating death rates death rates.

Stage II: Early Industrial Stage: Death rates fall because of improving economic and social conditions but birth rates remain high in a young population, e. g., Mexico.

Stage III: Industrial Stage: Birth rates begin to fall due to industrial development, contraception, education and jobs. Death rates also falls due to advanced medical technology, research and better living conditions. By 1945, the antibiotics permanently changed demography.

Stage IV: PostIndustrial Stage: Zero population growth, death rates falls drastically and the birth rate is low.