Birth weight is considered to be one of the most important determinants of health and child survival. Therefore, this study aimed to study to explore the risk of unintended pregnancy on infant weight based on the perception of the mother in Indonesia in 2010 along with the risk of the counfonders. This study is analytical research and used data from Indonesia Basic Health Survey. This study had a variable pregnancy outcomes, therefore a retrospective cohort study design was performed in this study. Based on the multivariable analysis was found the risk ratio gave low birth weight on mothers who experiences unintended pregnancy 1,27 times compared mothers who have experienced desired pregnancy after adjustment by age of mother, age of pregnancy, antenatal care and the amount of iron tablets. The probability derived giving birth to LBW babies in mothers during her intended pregnancy is 4.42% compared 3.52% among mothers with desired pregnancy with certain conditions, such as age group (20 - 34 years), adequate of pregnancy age, four times antenatal care frequency, and adequate of the amount of zinc tablets minimum in 90 days.