Family planning policy implemented over 30 years has generated a lot of only-children in China， and it has become a hot issue. The government loosened its single-child policy to allow a parent who has an only-child in their family to have another baby in 2014. Definitely this change will have an impact on the size and structure of the only-children. Thus， it is worth studying and forecasting under the new policy， especially in the context of ″less younger children and more aging population，″ so as to provide the basic information for the policy-maker to develop one-child parents pension policies in China． Based on 1% national population sample survey in 2005 and census data in 2010， we estimate the multi-age marriage probability among couples of double only-children， single only-children and non-only children， by following the idea and method of parity progression to measure out different number of couples who will be allowed to give only-children， or second children under the new fertility policy， and based on the number of second children and the parity-specific births to adjust dynamically the attributes of only children or non-only children， and to estimate the number of age-sex-specific only-children． The results show that by the end of 2013， the number of only-children had reached about 218 million， of which 69.0% lived in cities or towns， and 31.0 % in rural areas. With the implementation of the new fertility policy in 2014， the number of only-children will continue to grow， and the long term trend of lower birth rate is immutable. The number of only-children will reach 303 million by 2050， but 45 million less than under the one-child policy， which means less of only-child risky families and a more harmonious family structure conducive to future pension protection. The spatial distribution of only-children is heavier in our urban areas and eastern regions than other areas. There will be 303 million only-children in 2050， of which those in urban areas will account for 89.1% and the rural only-children for 10.9%. The only-children are mainly concentrated in the eastern China， followed by the Middle and West regions， and fewest in northeast China. However， the proportion of only-children in the eastern region will increase before decreasing， rise slowly in the Middle and West regions， and show a steady decline in the Northeast region. The disparity in provincial distribution of only-children is quite large， with over 10 million each existing in 12 provinces such as Jiangsu， Shandong but less than one million each in Tibet， Qinghai， and Hainan. The age structure of the only-children is dominated by those under 40 years of age at present， among whom the proportion of children aged 0-14 will show a rapid decline before a stable situation， the young and prime adults aged 15-39 will show a slow increase before a quick decrease， while the old adults aged 40 and above will rise continuously. The only-children aged 40 years and above will gradually replace the young in 2040 as the main body of only-children. As they grow old， the risk of death will increase， and the proportion of one-child parents who lose their only-child will increase too. Since the pension of the parents of only-children and dead only-children will become serious challenges， we should be prepared to deal with their social security in advance． The fertility policy simulation technology is used here， together with marriage probability of multi-age difference between couples， parity progression ratio and dynamic adjustment of the characteristics of only-children. The provincial-level forecast of the number of only-children under new fertility policy is conducted for the first time to provide the size and age structure of the only-children on the national， regional and provincial levels， in urban and rural areas. It should be noted that the statistical standard of only-children as well as the data are forecast under the condition that the current fertility patterns are unchanged， and the death probability of only-children is the same as non-only children．
姚引妹 李芬 尹文耀. 单独两孩政策下独生子女数量、结构变动趋势预测[J]. 浙江大学学报(人文社会科学版), 2015, 1(1): 94-104.
Yao Yinmei Li Fen Yin Wenyao. Forecast on the Size and Structure Trends of the Only-children under the New Birth Policy. JOURNAL OF ZHEJIANG UNIVERSITY, 2015, 1(1): 94-104.