中文摘要：

中国三十多年的出生性别比偏高引起了国内外广泛关注,一些研究认为计划生育政策的推行是中国的出生性别比偏高的重要原因之一。近几年来,学术界对生育政策放宽如何影响出生性别比形成了不同的观点,但这些观点缺乏实证研究的检验。本文用单独二孩政策实施后中部四个省的生育统计数据实证分析了政策调整对出生性别比的影响,研究表明：单独二孩政策实施以来,对出生性别比影响的方向是升高,但影响程度十分有限。导致上述结果的原因是单独二孩性别比在多数地区高于全部出生人口性别比,但单独二孩出生数占全部出生数的比重很小。单独二孩政策实施对控制出生性别比偏高工作带来了新的问题,相关部门应该积极应对。

英文摘要：

The high sex ratio at birth more than 30 years in China has aroused extensive concern at home and abroad.Some researches unfold that one of the major reasons is the implementation of the family planning policy in China.In recent years,the researchers hold different views on how the policy-loosening affects sex ratio at birth,but these ideas lack of empirical research to back.This paper analyzes the impact of policy changes on the sex ratio at birth on the basis of the fertility statistic in four central provinces in central China after the implementation of the selective two-child policy.The studies show that the trend of the influence of the implementation of the policy on the sex ratio at birth is increasing,but the degree of the influence is limited.The reasons of this phenomenon come from that the sex ratio at birth of the second party children in many areas is higher than the whole sex ratio at birth,but the number of the second party children accounts for a small proportion of all births. This paper analyzes the implementation of the selective two-child policy has brought new problems to the work of controlling the high sex ratio at birth,the government should respond actively.