Improved Fecundity in Northern China: A Secular Trend from 1980 to 2003.

This study aimed to assess the trend of human fecundity over time in China.This retrospective study was conducted in Tongliao, China. Couples who were married during the time period between January 1, 1981 and December 31, 2003 were considered eligible for this study. A total of 27,413 individuals provided valid information via house-to-house interviews. The 12-month cumulative pregnancy rate (CPR) and annual percentage change were used as the outcome measurements.There was a significant increase in the CPR over the five successive time groups. A break point in 1988 divided the entire study period into two distinct segments: 1981-1988, during which the CPR increased from 72.2% to 84.2%, and 1988-2003, during which the CPR increased from 84.2% to 87.2%.The findings were unlikely to be the result of biases, and could not be explained by increased medical treatment for infertility and changes in the prevalence of sexually transmitted diseases. Dramatic societal and behavioral changes due to the unique family planning policy and economic reform policies in China might have been the plausible reason for the results.