1. School of Nursing, University of São Paulo, São Paulo, Brazil
2. National Department of Maternal Health, Oswaldo Cruz Foundation, Sao Paulo, Brazil
3. Departamento de Enfermagem, Universidade Federal de São Carlos, São Carlos, Brazil
4. Kamiyama Consultoria em Estatística Ltda, Instituição, Sao Paulo, Brazil
5. Florence Nightingale Faculty of Nursing & Midwifery, King’s College London, London, UK