A new randomized, open-label French trial offers more evidence that the discontinuation of oxytocin treatment after the earliest stages of labor may be safe. Stopping oxytocin didn’t appear to affect neonatal outcomes, compared with continual use of the medication. However, the first stage of labor lasted slightly longer – not surprisingly – in those in the intervention group, and many of those who stopped oxytocin treatment resumed it later.
“Our trial did not show any impact of oxytocin discontinuation in the active [labor] stage on neonatal morbidity cesarean delivery, postpartum hemorrhage, birth experience, and postpartum depression,” said Aude Girault, MD, PhD, of Paris Cité University, in a presentation in San Francisco at the meeting sponsored by the Society for Maternal-Fetal Medicine.
The goal of the STOPOXY study is to build upon previous research that found oxytocin discontinuation didn’t boost the risk of cesarean delivery rates, uterine hyperstimulation, and abnormal fetal heart rate, Dr. Girault said. “These studies were underpowered to show any effects on neonatal morbidity,” so she and colleagues decided to dig deeper into the issue by launching the new trial.
From 2020 to 2022, researchers assigned 2,367 women who received oxytocin before 4 centimeters dilation to either continue with the drug (n = 1,192) or discontinue it before reaching 6 centimeters dilation (n = 1,175). Overall, the women were pregnant for the first time (around 55%) with a median age around 32 years and body mass index around 24.1 kg/m2. All had live, singleton, full-term babies.
More than a third – 37% – of those who discontinued oxytocin resumed treatment with the medication, while 5% of those in the control group stopped taking it.
The neonatal morbidity rate – defined via a composite variable based on umbilical arterial pH, umbilical arterial lactates, Apgar score, and/or neonatal ICU admission – was 10.0% in the intervention group and 10.1% in the control group (P = .94), the researchers reported. Cesarean delivery rates were similar (18.8% vs. 16.5%, respectively; P = .22). Apart from the duration of the active first stage, which was significantly higher in the intervention group (100 min [ interquartile range, 50-208 min] vs. 90 min [IQR, 45-150 min]; P = .001), there were no significant differences between the groups.
Dr. Girault said this increase in labor duration was “moderate and clinically debatable.”
In an interview, oncologist-gynecologist George Saade, MD, of the University of Texas Medical Branch, Galveston, noted that “oxytocin is frequently used for either induction or augmentation of labor ... with the goal of improving maternal and neonatal outcomes.”
Oxytocin itself is not expensive, Dr. Saade said. “However, when it is given, the patient requires more monitoring, which may increase cost.”
There’s debate over the proper use of oxytocin, which is available in a synthetic version as Pitocin, and researchers have been trying to understand whether it can safely be discontinued early in labor.
Potential side effects of oxytocin include heart disorders such as arrhythmia, asphyxia, neonatal seizure, and jaundice, low Apgar score, and fetal death. A boxed warning says: “Because the available data are inadequate to evaluate the benefits-to-risks considerations, oxytocin is not indicated for elective induction of labor.”
However, “overall oxytocin is commonly used and very safe as long as careful protocols are followed,” David N. Hackney, MD, MS, of University Hospitals Cleveland, said in an interview. “The medication itself does not have many negative side effects. With very high doses there can be a concern for water intoxication, though this is clinically very uncommon. Some prior studies have raised concerns about the use of oxytocin and subsequent long-term neurodevelopmental outcomes, though these associations are likely confounders and the mainstream opinion is that these are not truly biologically causative associations.”
A 2021 study in The BMJ randomly assigned 1,200 women to continue or discontinue oxytocin. There was a slight increase in cesarean sections in the discontinuation group but significantly lower risks of uterine hyperstimulation and abnormal fetal heart rate.
Dr. Hackney, who didn’t take part in the new study, said the trial is “well conducted and well executed.” However, it needs peer review before any of its findings should change practice.
He added that differences in delivery protocols between the United States and France should be considered. As he noted, Dr. Girault mentioned in a Q&A after her presentation that delayed second-stage labor is more common in France than in the United States.
The study was funded by the French National Ministry of Health. Disclosures for the authors were not provided. Dr. Saade and Dr. Hackney have no disclosures.