Prevalence, mortality and risk factors associated with very low birth weight preterm infants: an analysis of 33 years Julia Damiani Victora; Mariangela Freitas Silveira; Cristian Tedesco Tonial; Cesar Gomes Victora; Fernando Celso Barros; Bernardo Lessa Horta; Iná Silva dos Santos; Diego Garcia Bassani; Pedro Celiny R. Garcia; Marola Scheeren; Humberto H. Fiori;