Maternal risk factors associated with persistent placenta previa

Maternal risk factors associated with placenta previa are well documented in the literature. However, there are limited studies identifying maternal characteristics associated with the persistence of placenta previa. The objective of the study was to determine maternal characteristics associated with the persistent placenta previa.

A retrospective cohort study was conducted in which 705 pregnant women diagnosed with low-lying placenta or placenta previa between 17 and 24 weeks gestation were identified from a single institution between 2003 and 2017. The primary outcome included persistent placenta previa (i.e., persistent placental tissue within 2 cm of the internal os) at or after 36 weeks 0 days. Those with abnormal placentation (e.g., vasa previa, placenta accreta) or delivery prior to 36 weeks 0 days were excluded. Multivariable logistic regression modeling was utilized to determine significant maternal characteristics associated with persistent placenta previa among women diagnosed with either placenta previa or low-lying placenta.

Women with a prior cesarean delivery were seven times more likely to have persistent placenta previa (odds ratio, 7.0, 95% confidence interval, 3.7-13.1). A history of intrauterine curettage or evacuation in the setting of placenta previa increases the likelihood of persistent placenta previa almost 3-fold (odds ratio, 2.5, 95% confidence interval, 1.3-5.0).

To date, our study is the largest, retrospective cohort study assessing maternal risk factors associated with persistent placenta previa; and is the first to detect a statistically significant correlation between a history of intrauterine surgeries and persistent placenta previa.