Which second trimester placenta previa remains a placenta previa in the third trimester: A prospective cohort study

•The majority of the second trimester placenta previa will no longer overly the internal os in the third trimester.•The overlying distance of the placenta, a previous cesarean delivery and ART increase the risk of persistence of a placenta previa.•Women with a placenta previa overlying the internal os of the cervix < 14 mm or > 55 mm in the second trimester are at low-risk and high-risk respectively for persistence of the placenta previa. The far majority of women with a placenta previa in the second trimester will no longer have a placenta that overlies the internal os in the third trimester. Women with a placenta previa in the third trimester are at risk for complication such as preterm birth and blood loss. Four counselling purposes we aim to identify which women with a second trimester placenta previa have a low-risk and a high-risk for persistence of the placenta previa. A prospective cohort study of women with a placenta previa in the second trimester between 2014 and 2019. The odds for having a placenta previa in the third trimester were calculated for different baseline characteristics. Multilevel likelihood ratios for ranges of the placenta overlying the internal os in the second trimester and the corresponding ROC curve were calculated to identify the optimal cut-off values. We included 313 women with a placenta previa in the second trimester. The placenta was more frequently located on the posterior wall (62 %) than on the anterior wall (38 %). At evaluation in the third trimester, 37 women (14 %) still had a placenta previa. Women with a larger distance of the placenta overlying the internal os, women having a previous cesarean delivery and women after a conception with assisted reproductive technique had a significant higher risk of placenta previa persistence (p-values