Management of fetuses with apparent normal growth and abnormal cerebroplacental ratio: A risk-based approach nearterm.

Abstract

Cerebroplacental ratio (CPR) has been shown to be an independent predictor of adverse perinatal outcome at term and a marker of failure to reach the growth potential (FRGP) regardless of fetal size, being abnormal in compromised fetuses with birthweight above the 10th centile. The main aim of this study was to propose a risk-based approach for the management of pregnancies with normal estimated fetal weight (EFW) and abnormal CPR near term. This was a retrospective study of 943 pregnancies, that underwent an ultrasound evaluation of EFW and CPR at or beyond 34 weeks. CPR values were converted into multiples of the median (MoM) and EFW into centiles according to local references. Pregnancies were then divided into four groups: normal fetuses (defined as EFW ≥10th centile and CPR ≥0.6765 MoM), small for gestational age (EFW <10th centile and CPR ≥0.6765 MoM), fetal growth restriction (EFW <10th centile and CPR <0.6765 MoM), and fetuses with apparent normal growth (EFW ≥10th centile) and abnormal CPR (<0.6765 MoM), that present FRGP. Intrapartum fetal compromise (IFC) was defined as an abnormal intrapartum cardiotocogram or pH requiring cesarean delivery. Risk comparisons were performed among the four groups, based on the different frequencies of IFC. The risks of IFC were subsequently extrapolated into a gestational age scale, defining the optimal gestation to plan the birth for each of the four groups. Fetal growth restriction was the group with the highest frequency of IFC followed by FRGP, small for gestational age, and normal groups. The "a priori" risks of the fetal growth restriction and normal groups were used to determine the limits of two scales. One defining the IFC risk and the other defining the appropriate gestational age for delivery. Extrapolation of the risk between both scales placed the optimal gestational age for delivery at 39 weeks of gestation in the case of FRGP and at 40 weeks in the case of small for gestational age. Fetuses near term may be evaluated according to the CPR and EFW defining four groups that present a progressive risk of IFC. Fetuses in pregnancies complicated by FRGP are likely to benefit from being delivered at 39 weeks of gestation.