Research progress of cerebroplacental ratio in obstetric complications

Cerebroplacental ratio (CPR), defined as fetal middle cerebral artery pulsatility index (MCA-PI)/umbilical artery pulsatility index (UA-PI), quantifies intrauterine hemodynamic redistribution driven by the fetal brain-sparing response to placental insufficiency. With the advancement of ultrasonic technology and in-depth clinical research, CPR has been widely applied in early screening, condition assessment, prognosis evaluation and intervention guidance of various obstetric complications, especially showing unique clinical value in high-risk pregnancies such as fetal growth restriction, preeclampsia and hyperglycemia in pregnancy. For example, in fetal growth restriction (FGR), low CPR yields 78.5% sensitivity and 82.1% specificity for predicting intrapartum fetal distress, with an adjusted OR of 6.82 for composite adverse perinatal events. This review aims to collect literature about the roles of CPR in pregnancy complications. We consider all relevant articles in English from 1987 to 2026 through mainstream academic databases, including PubMed, Web of Science, CNKI and Wanfang Data. We systematically describe the physiological basis and measurement criteria of CPR, elaborates on its research progress in common obstetric complications, analyzes the controversies and deficiencies of current studies, and prospects its future clinical application, so as to provide theoretical and practical support for the precise management of high-risk obstetric pregnancies.