ABSTRACT Objective: to evaluate the association of Obstetric Nursing in the best practices of delivery and birth care in maternity hospitals. Method: a cross-sectional study, with 666 women selected for delivery. Parturition obstetric practices performed by professionals were categorized into: clearly useful practices that should be encouraged, practices that are clearly harmful or ineffective and that should be eliminated and practices used inappropriately at the time of parturition. Results: clearly useful practices were used in greater proportions in the hospitals that had Obstetric Nursing working, while clearly harmful practices and those used inappropriately were practiced in smaller proportions in hospitals that had Obstetric Nursing, both with statistical difference. Conclusion: institutions with Obstetric Nursing adopt better practices of delivery and birth care, based on scientific evidence, when compared to those that do not act.