The birth rate of China has tended to decline, except for some temporary reverses, for nearly half a century since the founding of the modern nation. Especially, the years since the 1970s have seen sharp drops. The average fertility rate for the 1950s was 5.87, which is almost the same level as the 5.68 of the 1960s. The fertility rate for the 1970s steadily declined to an average of 4.01, and that in the 1980s averaged below 2.50. According to the fourth population census, held in 1990, the national fertility rate is 2.25, with the regional lowest of 1.33 in Beijing, and the highest, of 4.22, in Tibet, which is almost double the national average. The birth rates in about a third of the regions of China were so low as to fall under the population replacement level.
Along with the decline in birth rates, mortality rates have also decreased, pushing up the average life expectancy of the population. The average life expectancy of Chinese men was 55.8 years, and that of Chinese women was 55.9 years. These increased to 66.3 years and 69.3 years respectively in 1981, then to 67.6 years and 70.9 years in 1990.
Sustainable rapid decline in the birth rate and continuous growth of life expectancy together imply fast aging of the future Chinese population. Various regional differences in age structures are seen in China. Migrations between urban and rural areas could be one reason, but a more important factor is considered to be the birth-rate gaps. Although aging of the Chinese population, as a whole, is still relatively minor, differences between urban and rural areas, or between regions, are rather great. The population's aging is expected to develop very fast in the years to come, and the reason for that is the continuous decline in the birth rate, which is a result of the population control carried out over more than 20 years.
Due to the declining birth rate under the population control policy, the age structure of the population has varied. As the composition of the Chinese population shows in the Table 1, the oldest age group of 65 and above accounted for 5.6% of the population in 1990, and increased to 6.7% in 1995, while the population index of old people reached 10% in 1995. The United Nations medium variant estimate ("World Population Prospects： The 1996 Revision") forecasts that the oldest age group of 65 and above in China will account for 10.8% of the total population in 2020, 14.4% in 2030, and 19.2% in 2050.
