Is fetal cerebroplacental ratio an independent predictor of intrapartum fetal compromise and neonatal unit admission?

Abstract

Objective: We sought to evaluate the association between fetal cerebroplacental ratio (CPR) and intrapartum fetal compromise and admission to the neonatal unit (NNU) in term pregnancies.

Study design: This was a retrospective cohort study in a single tertiary referral center over a 14-year period from 2000 through 2013. The umbilical artery pulsatility index, middle cerebral artery pulsatility index, and CPR were recorded within 2 weeks of delivery. The birthweight (BW) values were converted into centiles and Doppler parameters converted into multiples of median (MoM), adjusting for gestational age using reference ranges. Logistic regression analysis was performed to identify, and adjust for, potential confounders.

Results: The study cohort included 9772 singleton pregnancies. The rates of operative delivery for presumed fetal compromise and neonatal admission were 17.2% and 3.9%, respectively. Doppler CPR MoM was significantly lower in pregnancies requiring operative delivery or admission to NNU for presumed fetal compromise (P < .01). On multivariate logistic regression, both CPR MoM and BW centile were independently associated with the risk of operative delivery for presumed fetal compromise (adjusted odds ratio [OR], 0.67; 95% confidence interval [CI], 0.52-0.87; P = .003 and adjusted OR, 0.994; 95% CI, 0.992-0.997; P < .001, respectively). The latter associations persisted even after exclusion of small-for-gestational-age cases from the cohort. Multivariate logistic regression also demonstrated that CPR MoM was an independent predictor for NNU admission at term (adjusted OR, 0.55; 95% CI, 0.33-0.92; P = .021), while BW centile was not (adjusted OR, 1.00; 95% CI, 0.99-1.00; P = .794). The rates of operative delivery for presumed fetal compromise were significantly higher for appropriate-for-gestational-age fetuses with low CPR MoM (22.3%) compared to small-for-gestational-age fetuses with normal CPR MoM (17.3%).

Conclusion: Lower fetal CPR, regardless of the fetal size, was independently associated with the need for operative delivery for presumed fetal compromise and with NNU admission at term. The extent to which fetal hemodynamic status could be used to predict perinatal morbidity and optimize the mode of delivery merits further investigation.

Keywords: Doppler; cerebroplacental ratio; fetal compromise; neonatal unit admission; small for gestational age.