Chart 2. List of excluded studies.

Study		Reason
1	Machado, O., 2017. [Factors associated with uterine atonia in the postwork of the Hospital Uldarico Rocca Fernández in Villa el Salvador, in the period January - December 2014]. Repository of the San Martín de Porres University. https://repositorio.usmp.edu.pe/handle/20.500.12727/2684?locale-attribute=de	The study is a thesis published in a repository.
2	Salazar de Dugarte G, González de Chirivella X, Faneite Antique P. Incidencia y factores de riesgo de macrosomía fetal. Rev Obstet Ginecol Venezuela. 2004; 64(1):15–21.	Does not operationally define the variable postpartum hemorrhage.
3	Galarza MP de L. Indicadores clínico epidemiológicos y materno-fetales de atonía uterina en puérperas post cesárea primaria en una clínica privada de agosto 2017–agosto 2018. Rev Fac Med Humana. 2019; 19(2):7–7.	Does not operationally define the variable postpartum hemorrhage.