The study is based on determining the difference in hemoglobin in the third trimester of pregnancy and the immediate puerperium of childbirths attended at the Hospital de Apoyo San Francisco, during 2018, located in the VRAEM area, a vulnerable area due to the level of poverty and exposure of the area. The type of the research was observational, retrospective longitudinal section in related samples, the study has the descriptive level, it has a sample of 107 childbirths, 55 vaginal and 52 cesarean, the documentary review technique was used, the data was analyzed with the statistical program "R" for data analysis, the non-parametric test Wilcoxon was used. Results: a difference of 1.52 g/dl has been found between hemoglobin of the third trimester of pregnancy 11.89 g/dl and immediate puerperium 10.37 g/dl; when analyzing the difference in vaginal childbirths, hemoglobin in the third trimester was found at 11.90 g/dl and the immediate puerperium was 10.65 g/dl, and in cesarean childbirths was 11.94 g/dl in the third trimester of pregnancy and 10.14 g/dl in the immediate puerperium, finding differences of 1.52 g/dl in vaginal childbirths and 1.8 g/dl in cesarean. Conclusion, there is a significant difference in hemoglobin in the third trimester and postpartum at a p-value of 0.05, being higher in cesarean childbirths; the average postpartum hemoglobin denotes anemia despite the fact that the blood losses were within normal parameters, which indicates that it must achieve that the pregnant women reach the third trimester of pregnancy with at least 13 g/dl of hemoglobin.