Placental basal plate with attached myofibers and adverse pregnancy outcomes: A systematic scoping review

The finding of basal plate myometrial fibers (BPMF) delivered with the placenta has been associated with many different pregnancy and delivery complications. This study aims to evaluate the clinical utility of this histopathological finding in obstetrics.

We searched PubMed, Google Scholar, and Embase for studies published in English reporting an association between obstetric complications and placental BPMF, using combinations of relevant medical subject heading terms and keywords, published between March 1996 and December 2025. Study characteristics were evaluated by two independent reviewers using a predesigned protocol. The PRISMA Extension for Scoping Review (PRISMA-ScR) was used to extract data and report the results.

Sixteen studies met our eligibility criteria for inclusion in this review. There were five cohorts and 11 studies, involving 5770 participants from four different countries. Nine studies reported on the association between BPMF on histopathologic examination in the setting of a delivered placenta and maternal or fetal pregnancy and delivery complications, and the remaining seven studies investigated the association between BPMF at birth in the index pregnancy and abnormal placental attachment at the next delivery. The most common prenatal and perinatal disorders were hypertensive disorders of pregnancy, placenta previa, preterm delivery, pre-labor rupture of the membranes, suspicion of intrauterine infection, diabetes, stillbirth, and fetal growth restriction, and the most common intrapartum complications were placental abruption and placental retention. A higher incidence of abnormal placental attachment was reported in the subsequent pregnancy in cases where BPMF were found in the first pregnancy, but wide heterogeneity was observed across the included studies, particularly in the clinical criteria used to report placental attachment at delivery and interpretations of corresponding results.

The clinical usefulness of reporting on BPMF in delivered placentas from pregnancies complicated by maternal or fetal disorders is currently difficult to evaluate due to variability in inclusion criteria, methodological protocols, and reported outcomes. The study of BPMF in delivered placentas may help fill evidence gaps in our knowledge of the pathophysiology of placental-related pregnancy disorders involving the uteroplacental interface and the link between these disorders and long-term maternal cardiovascular complications.