Clinical Correlates of Placenta Accreta Spectrum Disorder Depending on the Presence or Absence of Placenta Previa: A Systematic Review and Meta-analysis

To evaluate whether there are differences in risk factors and maternal outcomes of pregnancies complicated by placenta accreta spectrum depending on the presence or absence of placenta previa. We performed a systematic search in Medline, EMBASE, ClinicalTrials.gov , and Web of Science from inception through April 25, 2022, without language or date restrictions. Search strategy included the key words "placenta accreta," "placenta increta," "placenta percreta," "adherent placenta," "invasive placenta," "abnormal placent*," "placenta previa," and "marginal placent*." Of the 1,122 articles screened, seven studies were included in the final review. Studies were included if they compared the risk factors and maternal outcomes of pregnancies complicated by placenta accreta spectrum depending on the presence or absence of placenta previa. A random-effects model was used to pool the mean differences or odds ratios (OR) and the corresponding 95% CIs using RevMan software. A total of 3,342 pregnancies complicated by placenta accreta spectrum were included in the meta-analysis (2,365 without previa and 977 with previa). Pregnancies complicated by placenta accreta spectrum without previa were more likely to have been conceived by in vitro fertilization (IVF) (OR 3.11, 95% CI 1.93-5.02, P