Objective: To determine the cortisol level of patients who make use of the Obstetric Psychoprophylaxis (OPP) service in a first-level health center, February-May 2018. Material and methods: Descriptive, prospective, cross-sectional. Results: 68.75% of pregnant women have a stable conjugal relationship, while 25% are single and 6.25% separated, 50% have a higher education degree and 50% have a secondary education degree. Apparently, cortisol does not change according to gestational age, however, the number of OPP sessions influences the level of cortisol, so more assisted sessions means less cortisol. Conclusion: the greater exposure to obstetric psychoprophylaxis, the less levels of cortisol am (morning) in serum are observed. It could be due to psychoprophylaxis has a component that works the mental state; further studies are recommended.