Objectives To estimate the cost-effectiveness of administering calcium (1200 mg per day) starting in week 14 of pregnancy to all pregnant women compared to not supplying it to reduce the incidence of preeclampsia. Methods A decision tree was built in TreeAge® with outcome measured in life years gained (LYG) associated with the reduction in maternal deaths. Costs were included from the perspective of the health system in Colombia and expressed in Colombian pesos in 2014 (COP). The discount rate was 0 %. We performed sensitivity univariate and probabilistic analyses for costs and effectiveness. Results Compared to no intervention, calcium supplement is a dominant alternative. If the incidence of preeclampsia is lower than 51.7 per 1 000 pregnant women or the cost per tablet of calcium of 600 mg is greater than COP $507.85, calcium supplement is no longer a cost-effective alternative in Colombia for a threshold of COP $ 45 026 379 (3 times the Colombian per capita GDP of 2013 per LYG). Conclusions Supplying calcium to all pregnant women from week 14 of gestation is a dominant alternative compared to no intervention, which saves 200 LYG, while it decreases costs to the order of COP$5 933 million per 100.000 pregnant women.