Re-Evaluating the Contraction Stress Test for Term Fetal Growth Restriction Fetuses: A Retrospective Study.

Background

Fetal growth restriction (FGR) is associated with increased perinatal morbidity and mortality, yet optimal intrapartum management remains debated. The contraction stress test (CST) has been proposed as a tool to assess fetal tolerance to labor, but its prognostic value in FGR pregnancies is unclear. This study aimed to evaluate the utility of CST in predicting perinatal outcomes among term fetuses with FGR and to compare these outcomes with those of small-for-gestational-age (SGA) fetuses.

Methods

We conducted a retrospective cohort study of term singleton deliveries at a tertiary care center over a two-year period. FGR was defined as birthweight below the 3rd percentile or, prenatally, below the 10th percentile with abnormal Doppler findings. SGA fetuses were defined as birthweights between the 3rd and 10th percentiles. Participants were stratified into the following three groups: (1) FGR with a negative CST result, (2) FGR without CST, and (3) SGA without FGR. The primary outcome was the rate of emergency cesarean delivery. Secondary outcomes included a composite of neonatal adverse events (Apgar score < 7 at 5 min, umbilical cord pH < 7.1, NICU admission, prolonged neonatal hospitalization, intubation, or intraventricular hemorrhage) and a combined metric of neonatal and maternal adverse events.

Results

A total of 1688 term singleton pregnancies were included in this analysis, comprising 33 cases of FGR with negative CST results, 275 cases of FGR without CST, and 1123 cases classified as SGA. Emergency cesarean delivery rates were comparable between FGR with negative CST (15.2%) and FGR without CST (14.9%), both were significantly higher than in the SGA group (9.7%, p = 0.025). Composite neonatal adverse events did not differ significantly between the FGR groups (21.2% vs. 24.7%) but were more frequent than in the SGA group (8.1%, p < 0.001). Similarly, the incidence of combined neonatal and maternal adverse events was not different between the FGR groups (30.3% vs. 33.5%) yet exceeded that of the SGA group (15.1%, p < 0.001).

Conclusions

In this cohort, a negative CST performed prior to labor induction did not reduce the risk of adverse maternal or neonatal outcomes in pregnancies complicated by FGR. These findings indicate that routine use of CST may offer limited prognostic benefit in the evaluation of term FGR, highlighting the necessity for further studies to establish evidence-based surveillance and management strategies for this high-risk group.