Quality vs Quantity of Life

To achieve the greatest happiness for all, there must be a balance between quantity and quality of life. Family planning (contraception, abortion) favors quality over quantity, destroying life that would be of low quality, until a later time at which it can be created at higher quality. If we favored quantity over quality, then we should take an example from India and China, and we would still have the population boom that we had in the 20th century.