OBJECTIVES: Unplanned pregnancy (UP) is a public health problem that impacts women, families and countries, with social, health and economic repercussions. At the present, there are publications that estimate the economic burden of UPs in other countries, however, there are no local data, thus models are needed to approximate the costs in Chile, using RGD-WinSIG for cost information. This is our first goal. The UPs proportion related to the failure of compliance in the population under fertility control in the Public Health System (PS) was also calculated as second objetive

METHODS The proposed model considered direct costs of pregnancy and their annual outcomes obtained mostly by RGD-WinSIG indexed by the UPs percentage. This model could be reproducible in any country that has RGD-WinSIG, We used WHO data for calculate failure compliance.

RESULTS The economic burden for our country is approximately USD 278 million per year. Around USD 129 million is the burden in PS by failure of compliance inherent on contraceptive methods, most of them short-acting. In the PS, the 47.7% of UPs are produced using short-term contraceptive methods: 1.7% for faults with perfect use and 46% for failures in compliance. This number contrasts with the 1.3% of UPs due to total failures of long acting reversible contraception (LARC): 1.0% failures with perfect use, mainly Cu IUD, and only 0.3% of Ups produced by compliance failure of all LARC

CONCLUSIONS According our findings, in Chile will be necessary to give greater emphasis to LARC in public policies of family planning.