“…As in our previous review [ 4 ], we included observational studies (cross-sectional, cohort studies, and case-control) on placenta previa among pregnant women meeting the clinical diagnostic criteria [ 26 , 27 ] conducted in mainland China, providing they reported the prevalence or incidence of placenta previa. We excluded meeting abstracts; case reports and case series; poster presentations; and articles we could not access or that had incomplete data.…”