Oxytocin discontinuation during active labor improves fetal heart rate patterns and reduces decelerations
Background
Oxytocin is widely used to augment uterine contractions during labor, but its administration is associated with adverse fetal outcomes. Concerns include fetal heart rate (FHR) abnormalities and potential neonatal morbidity, which may stem from excessive uterine activity or reduced placental perfusion. Current standard-of-care often involves continuous oxytocin infusion, yet strategies to mitigate these risks are needed. This study investigates whether discontinuing oxytocin at the onset of active labor can improve FHR patterns and uterine contractility, addressing a critical gap in labor management protocols.
Study Design
This pre-specified ancillary analysis of the STOPOXY randomized trial (NCT04935242) included 284 women from six French maternity units. Participants who received oxytocin before 4 cm dilation were originally randomized (1:1) to either oxytocin discontinuation or continuation. For this analysis, women from the per-protocol discontinuation group were selected. Using a paired before-and-after design, FHR parameters (classified by FIGO criteria) and uterine activity were compared during the 60 min preceding versus the 60 min following oxytocin discontinuation. Independent obstetricians, blinded to neonatal outcomes, assessed changes in FHR patterns, categorized as no change, improvement, or deterioration.
Results
Following oxytocin discontinuation, significant improvements in fetal heart rate patterns and uterine activity were observed. Mean FHR increased from 135 bpm to 137.5 bpm (p < 0.002), indicating a slight but statistically significant rise. FHR variability also significantly changed (p = 0.010), with a lower rate of reduced variability (decreasing from 3.9% to 2.5%) and a higher rate of normal variability (increasing from 48.2% to 53.3%). This suggests a more robust and reassuring fetal status. Uterine activity decreased, with fewer uterine contractions per 10 minutes and lower contraction intensity. Most notably:
The proportion of tracings exhibiting decelerations significantly decreased from 64.1% to 48.6% (p < 0.001), representing a 15.5% absolute reduction in a key indicator of fetal distress.
Key Findings
- Mean fetal heart rate increased by 2.5 bpm after oxytocin discontinuation (p < 0.002).
- Rate of reduced FHR variability decreased from 3.9% to 2.5%.
- Rate of normal FHR variability increased from 48.2% to 53.3%.
- Proportion of FHR tracings with decelerations decreased by 15.5% (64.1% to 48.6%; p < 0.001).
- Uterine activity decreased following oxytocin discontinuation.
Why It Matters
This study provides compelling evidence that discontinuing oxytocin at the active phase of labor can improve fetal well-being, potentially reducing the risk of adverse neonatal outcomes. Clinicians may consider implementing oxytocin discontinuation as a strategy to optimize FHR patterns and reduce decelerations during labor. This could lead to revised labor management protocols, particularly for women already receiving oxytocin augmentation. While this is an ancillary analysis, the findings suggest a practical, non-pharmacological intervention that could enhance safety without necessarily prolonging labor significantly. Further research is needed to confirm these benefits in broader populations and assess long-term neonatal outcomes, but the immediate impact on FHR is clear.
oxytocin
labor-induction
fetal-heart-rate
uterine-contractility
obstetrics
clinical-trial