Material and methods
This was an observational cohort study with retrospective
analysis including all vaginal live births that occurred between
August 2013 and May 2014. We choose this period randomly.
The study was approved by the Research Ethics Committee of
the Universidade Federal de Minas Gerais in accordance with
the Code of Ethics of the Declaration of Helsinki. Because it
was a secondary data analysis, the need for a woman’s individual
signature of consent was waived. Register number:
CAAE 10286913.3.0000.51.49