The risk of preterm birth associated with a low cerebroplacental ratio.

This paper investigated whether a cerebroplacental ratio (CPR) < 10th centile (measured between 23 + 0-36 + 0 weeks gestation) is predictive of any preterm birth, birth within 2 weeks of the ultrasound scan or spontaneous preterm birth. This was a retrospective cohort study of 8977 women during 2014 and 2015 at a major tertiary referral hospital. Selection criteria included women who had a nonanomalous, singleton fetus and underwent an ultrasound scan between 23 + 0-36 + 6 weeks gestation. A low CPR increased the risk of preterm birth or birth within 2 weeks of the scan with the highest odds of birth within 2 weeks seen at 28-week gestation (odds ratio (OR) 3.78, 95%CI 1.63-8.77) - the mode of delivery was most likely emergency caesarean section for nonreassuring fetal status (aOR 2.11, 95%CI 1.69-2.64, p < .001). Neonatal outcomes were worse in the low CPR cohort particularly with higher odds of death (aOR 2.30, 95%CI 1.46-3.63) and composite adverse outcome (aOR 1.46, 95%CI 1.24-1.73). The low CPR cohort had a significantly shorter interval to delivery (Cox Proportional Hazard - aHR 1.41, 95%CI 1.33-1.51, p < .001) and earlier gestation at birth. A low CPR is associated with an increased risk of preterm birth and birth within 2 weeks but not spontaneous preterm birth.