Does gestational age at term play a role in the association between cerebroplacental ratio and operative delivery for intrapartum fetal compromise?

INTRODUCTION

To assess the impact of gestational age at term on the association between cerebroplacental ratio (CPR) and operative delivery for intrapartum fetal compromise (IFC) and prognostic performance of CPR to predict operative delivery for IFC.

MATERIAL AND METHODS

This was a retrospective cohort study including 2052 singleton pregnancies delivered between 37 and 41  weeks of gestation in a single tertiary referral center over an 8-year period. CPR was measured within 1 week of delivery. IFC was defined as the presence of persistent pathological cardiotocography pattern or the combination of pathological cardiotocography pattern and fetal scalp pH < 7.20. Operative delivery included instrumental vaginal delivery and cesarean section. Pregnancies were grouped according to birthweight (small for gestational age [SGA, birthweight <10th centile] and appropriate for gestational age [AGA, birthweight 10th-90th centile]) and gestational age by week at delivery. Rates of operative delivery were compared between the subgroups. Prognostic value of CPR was assessed using receiver operating characteristic curve.

RESULTS

Of the study cohort, 308 (15%) had a CPR <10th centile, 374 (18%) operative delivery for IFC, and 298 (15%) were SGA at birth. Overall, the rates of operative delivery for IFC were higher in the low CPR group both in SGA (35% vs. 22%; p = 0.023) and in AGA (23% vs. 16%; p = 0.007). According to gestational age by week at delivery, fetuses with low CPR showed higher rates of operative delivery for IFC with advancing gestational age, mainly in pregnancies delivered at 40 weeks (54% vs. 23%; p = 0.004) and at 41 weeks (60% vs. 19%; p = 0.010) for SGA and at 41 weeks (39% vs. 20%; p = 0.001) for AGA. The predictive value of CPR remained stable throughout term and was poor both in SGA and in AGA.

CONCLUSIONS

Both SGA and AGA fetuses with low CPR showed higher rates of operative delivery for IFC at term with advancing gestational age. Prognostic value of CPR throughout term was poor.