文章從社會動力的視角建立生育率演化的解釋模型,認為影響生育行為的3種基本社會動力是生育意愿力、節育阻隔力和競爭偏好力,它們此消彼長的演替推動了人口發展經歷自然生育、節制生育和抑制生育3個歷史階段。計劃生育政策是影響中國生育行為的第4種動力,伴隨計劃生育的倡導、推行以及單獨二孩和全面二孩的政策松弛,中國的生育率發生了較為復雜的變化;1990年代初期市場經濟體制的確立激發了競爭偏好力。文章依據華東地區的2017年生育狀況抽樣調查數據,揭示一般生育率、婚后生育率及其孩次模式的演化,在空間上表現為以上海為中心向南北兩側遞變的緯度地帶性。文章按月份進度考察出生數對政策松弛的響應節奏,確認了計劃生育政策調整的社會有效性。

This paper constructs an explanatory model of fertility changes based on social dynamics, which consists of three factors affecting human reproductive behavior, including fertility intentions, contraceptive barriers and competing preferences. The changes in the relative effects among these three factors contribute to three stages of fertility change in human history: natural fertility, shrinking fertility and suppressed fertility. In China, family planning policy is the fourth factor. With the promotion, implementation and relaxation of the family planning policy, Chinese reproductive behaviors have adjusted accordingly, leading to fluctuating fertility rates. The building-up of market economy in early 1990 s stimulated the competing preferences. Based on data for East China from the 2017 fertility survey, this paper examines trends in total fertility rate, marital duration-specific fertility rate and parity-specific total fertility rate. With Shanghai in center, fertilities by provinces differ latitudinally. We also show the changes of monthly distribution of births since 2012 to see the influence of family planning policy adjustment.