Complications resulting from unsafe abortion are among the major complications which account for nearly 75% of all maternal deaths. Unsafe abortion is risky for women with an unintended pregnancy. Unintended pregnancy is one of the important issues in public health because there is a negative relationship with the health and social impacts for both mother and children. This study aims to determine trends and analyses the determinants of unintended pregnancy in married woman aged 15-49 in Indonesia. The secondary data used in this study are Indonesia Demographic and Health Survey (IDHS) 2002/03, 2007, and 2012 to display the trends and IDHS 2012 to analyze factors associated with unintended pregnancy. This study is a quantitative study using cross sectional design with married woman aged 15-49 years who had pregnancy/birth and currently pregnant at the time of survey as the study population. Data analysis was done with complex sample from univariate, bivariate by using chi square analysis, and multivariate by using multiple logistic regression analysis. The results shows the increase and decrease of unintended pregnancy based on IDHS 2002/03, 2007, and 2012 (17,1%, 20,3%, 14,7%). The result of the study based on IDHS 2012 shows that the variables significant associated to the incidence of unintended pregnancy included the use of planning methods (PR=1,91), knowledge of contraception methods (PR=0,73), age (PR=1,97), parity (PR=3,25), birth spacing (PR=0,76), residents (PR =1,29), age at first marriage (PR=1,33), knowledge of ovulation cycle (PR=1,31), woman participation in household decision making (PR=1,52). Parity is the most dominantly influencing variable with unintended pregnancy incidence after other variables control (PR=2,33). Contraception program for fertile couples is important to reduce the unintended pregnancy issue by focusing on the effectivity of KB or birth control method, ideal pregnancy planning, and related mother-infant health program so that the welfare of the family can be maintained and improved, decreasing the fertility rate, unsafe abortion and maternal mortality.