Longitudinal change in cerebro-placental ratio (CPR) between 37 and 40 weeks of pregnancy is associated with non-reassuring fetal status and increased risk of cesarean section.

Objective: To evaluate in low-risk pregnancies if longitudinal change in cerebro-placental ratio (CPR) between 37 and 40 weeks of pregnancy is associated with cesarean section (CS) for non-reassuring fetal status (NRFS) during labor.

Methods: This is a prospective observational study of women with singleton low-risk pregnancies who underwent an ultrasound scan at 36 + 0 to 37 + 6 and 39 + 0 to 41 + 6 weeks of pregnancy, when the CPR was calculated from the middle cerebral artery (MCA) and umbilical artery (UA) pulsatility indices. Managing professionals were kept blinded to the Doppler results.

Prescriptive Reference Standards of Third-Trimester Cerebroplacental Ratio and Its Physiological Determinants.

Objective: To construct valid reference standards reflecting optimal cerebroplacental ratio and to explore its physiological determinants.

Methods: A cohort of 391 low-risk pregnancies of singleton pregnancies of nonmalformed fetuses without maternal medical conditions and with normal perinatal outcomes was created. Doppler measurements of the middle cerebral artery and umbilical artery were performed at 24-42 weeks.