INTRODUCTION: Every day, 800 women die for pregnancy causes around the world, 99% of those in developing countries. The multiple organ dysfunction syndrome (MODS) occurs in 15% of patients in critical care, with a related mortality up to 80%. Some values of arterial blood gas (ABG) analysis has been proposed in few publications in obstetric patients and its relationship with bad outcomes. METHODS: The aim of this study was to describe blood gas thresholds as a risk to develop MODS in obstetric patients. A retrospective case-control study was conducted in four hospitals of Bogota, Colombia, between 2008 and 2014. Logistic regression analysis was conducted. RESULTS: We collected information form 277 cases and 558 controls, of them, 84.9% was pregnant and 15.1% in the puerperium. The mean age was 27.8 years old (SD 7.3), the main diagnosis were hypertensive disorders (52.4%), bleeding (12.2%) and sepsis (12.2%). 490 patients had at least one ABG test, pH, PO2, PCO2, lactate and base deficit were measured. A multivariate analysis was performed, with strata by every main diagnosis as mentioned before. Association with MODS was found in lactate higher than 1.2 mmol/L (OR 2.2 95%CI 1.5-3.4, p < 0.000) and pH less than 7.35 (OR 5.2 95%CI 2.6-10.6, p < 0.000) for patients with preeclampsia; for hemorrhage a base deficit 9 (OR 2.0 95%CI 1.2-3.3, p < 0.006) was founded. There was no association with sepsis founded. CONCLUSION: Patients with MODS and preeclampsia the better ABG predictors were lactate and pH values, and for patients with hemorrhage, base deficit was identified. Prospective studies are needed.