1. Department of Obstetrics and Gynecology, Municipal Hospital of Huambo, Huambo, Angola.
2. Faculty of Medicine, University José Eduardo dos Santos, Huambo, Angola.
3. Heart Institute, Clinic Hospital of the Medical School of the University of Sao Paulo, Sao Paulo, Brazil.
4. Department of Physiology, Faculty of Medicine, Agostinho Neto University, Luanda, Angola.