SIX months ago, the Chinese Communist Party newspaper, People's Daily, carried its first editorial on birth control. Asserting that China's population is increasing by more than 13,000,000 per year and that economic development cannot yet catch up with this rapid multiplication, the editorial urged the Government to spread the use of birth control and to encourage youths to postpone marriage until age 25. This authoritative statement of policy was not the first indication of Red China's concern with population.