生育水平、性别偏好和出生性别比——兼论出生性别比的监测方法

Fertility Level,Sex Preference and Sex Ratio at Birth

本研究以马-冯-陈模型为定性基础,认为一定人口的出生性别比并非固定不变,而是受到生育水平的影响。当无性别偏好时,生育水平主要通过改变不同孩次占出生人口比例的方式影响出生性别比;当有性别偏好时,生育水平既影响不同孩次占总出生人口的比例,又影响不同孩次的出生性别比,从而对总出生性别比产生影响。对于没有性别偏好和性别选择行为的人口,生育水平变化是引起出生性别比波动的主要原因。有性别选择行为时,生育水平变化对出生性别比的影响较小,性别选择行为是出生性别比异常的主要原因。监测以"曾生子女孩次和性别次序"为条件划分的人群,可以有效而便捷地判断出生性别比变化趋势。

The sex ratio at birth of a given population is not fixed, but affected by the fertility level. Without gender preference, the effect of fertility level on SRB is arisen from the change of composition of birth-order-specific children. When taking into account the gender preference, fertility level affects not only the proportion of birth-order-specific children to total births, but the sex ratio of birth-order- specific children. Fertility rate change is the main reason of fluctuations of the SRB in the countries without gender preference. However, the change of fertility level has a little affect on SRB, and the sex selection is the main reason for the abnormal change of SRB in the countries with gender preference.