What is the purpose of the Hatchery and Conditioning Center?

In Brave New World, the Central London Hatchery and Conditioning Centre is the site of all reproduction of human life.

There ova are kept at "blood-heat" and sperm frozen. Once the ova are fertilized, they are returned to the incubators where the Alphas and Betas are allowed to remain until they are "definitely bottled." The Gammas, Deltas, and Epsilons are brought out after thirty-six hours in order to undergo the Bokanovsky Process.

The Bokanovsky Process is a scientific process in which an egg proliferates into as many as ninety-six buds which will become human beings through a series of arrests of development. These human beings then become Gammas, Deltas, or Epsilons through this process of genetic engineering. Their level of intelligence is much lower than that of the Alphas and Betas, who will be the leaders of the society. 

In the State Conditioning Centres, babies are conditioned through electric shocks to hate certain things, such as books and flowers. There are a number of conditioning sessions conducted, and there is sleep-teaching, or hypnopaedia, in which children are conditioned while they are asleep. Eventually, then, a child's mind is formed from the suggestions.

By using this system of controlling the intelligence of its people in the Social Predestination Room and through the conditioning sessions and hypnopaedia, the New World maintains "social stability."