Objective To analyze and compare the frequency of cesarean sections and vaginal deliveries through the Robson Classification in pregnant women attended at a tertiary hospital in two different periods. Methods Cross-sectional, retrospective study of birth records, comprising 4,010 women, conducted from January 2014 to December 2015 in the only public regional referral hospital for the care of high- risk pregnancies, located in Southern Brazil. Results The overall cesarean section rate reached 57.5% and the main indication was the existence of a previous uterine cesarean scar. Based on the Robson Classification, groups 5 (26.3%) and 10 (17.4%) were the most frequent ones. In 2015, there was a significant increase in the frequency of groups 1 and 3 (p < 0.001), when compared with the previous year, resulting in an increase in the number of vaginal deliveries (p < 0.0001) and a reduction in cesarean section rates. Conclusion The Robson Classification proved to be a useful tool to identify the profile of parturients and the groups with the highest risk of cesarean sections in different periods in the same service. Thus, it allows monitoring in a dynamic way the indications and delivery routes and developing actions to reduce cesarean rates according to the characteristics of the pregnant women attended.

Pregnancy is characterized by changes in various organs, triggering changes in the use of energy substrates and increased oxygen consumption. In addition, gestation is an oxidative event that can be assessed by the relationship between free radicals and antioxidants produced by the body. Excessive production of free radicals has detrimental effects such as damage to enzymes, carbohydrates, and DNA. Thus, the objective of this study was to evaluate the oxidative status and antioxidant responses throughout pregnancy through a longitudinal study. Reactive oxygen species were analyzed by means of thiobarbituric acid reactive substances and nitric oxide, the antioxidant system through vitamin C, sulfhydryl groups, total antioxidant capacity, and ferric reducing ability of plasma as well as enzymes such as catalase and delta-aminolevulinate-dehydratase in pregnant women in the three gestational trimesters (n = 30). According to the results, the markers of oxidative damage showed significant differences in the different gestational trimesters where they were increased in the second trimester when compared to the first trimester. The antioxidant defenses responded differently in each gestational trimester, suggesting a response pattern to try to combat the damage caused by free radicals, in order to stabilize the increase of oxidative stress caused in the second gestational trimester.