Abstract: Objective Explore the risk factors for spontaneous abortion of women at reproductive age.Methods By using the data of National Demographic and Reproductive Health Survey in 1997 and the univariate and multiple logistic regression model the authors anayzed the risk factors for spontaneous abortion of 7 293 married women,12 441 pregnancy outcomes between 1988 and 1997.Results The national spontaneous abortion rate was 4.26 percent.There existed regional differences,of which the married women in North China had the highest spontaneous abortion rate.And with the increase of age at the first marriage and of the number of pregnancies,the risk for at least one spontaneous abortion increased significantly.