Objective: to understand from the complex perspective the connections established between the Strategic Directions for Strengthening Nursing and Midwifery, delimited by the World Health Organization; to discuss the implications of these strategies for the investment of human resources in nursing and midwifery, with a view to strengthening the technical health capacity to face global health demands. Method: a documentary research, carried out from official WHO documents, from September to October 2019. A categorical analysis technique was performed, and the interpretation of the data was achieved based on the theoretical framework of Complexity. Results: three interdependent categories were defined, namely: challenges for the training of human resources in nursing and midwifery in order to meet the needs for global health; challenges for the development of the work of nursing and midwifery professionals in different contexts of practice; challenges for governments, leaders and health services to strengthen human resources in nursing and midwifery. Conclusion: the strategic directions corroborate the complex perspective because they value multidimensionality in the challenges for the professional practice of nurses and obstetricians. However, these challenges are also related to contextual, political, and leadership factors.