Can oxytocin be discontinued during active labour?
Discontinuing oxytocin during the active stage of labour appears safe, according to the STOPOXY trial presented at SMFM 2023.
Oxytocin is a recombinant hormone that induces or strengthens uterine contractions in pregnant women – this is either to aid labour and delivery or control postpartum bleeding.
In the study, discontinuing oxytocin during the active stage of labour did not affect neonatal outcomes compared with continuous use. However, the first stage of labour lasted slightly longer in the intervention group.
“Our trial did not show any impact of oxytocin discontinuation in the active [labour] stage on neonatal morbidity, caesarean delivery, postpartum haemorrhage, birth experience, and postpartum depression,” reported Dr Aude Girault of Paris Cité University in Paris, France. [SMFM, abstract OPS-4]
Oxytocin is effective in increasing the frequency and intensity of uterine contractions during the antepartum period, thus reducing labour duration. However, it can be associated with foetal and maternal complications, added Girault.
Digging deeper into 'oxy' use
Researchers have been trying to understand whether oxytocin can be safely discontinued in early labour. However, previous studies evaluating discontinuation of oxytocin were underpowered to show a reduction in neonatal morbidity. “Hence, we sought to evaluate the impact of discontinuing oxytocin during the active phase of labour on neonatal outcomes,” she said.
From 2020 to 2022, 2,367 women who received oxytocin before 4 centimetres dilation were assigned to either discontinue (n=1,175 intervention group) or continue (n=1,192 control group) the drug before reaching 6 centimetres dilation.
Overall, there were more primiparous women (55 percent) in the cohort. Median age was 32 years. BMI was 24.1 kg/m2. All had live, singleton, full-term newborns.
Thirty-seven percent of women who discontinued oxytocin resumed the treatment later. Five percent of women in the control group stopped taking it.
No significant differences
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 percent in the intervention group and 10.1 percent in the control group (p=0.94), said Girault.
Caesarean delivery rates were comparable between groups (18.8 percent vs 16.5 percent, respectively; p=0.22). Apart from the duration of the active first stage, which was significantly longer in the intervention group (100 min [interquartile range, 50–208 min] vs 90 min [IQR, 45–150 min]; p=0.001), there were no significant differences in outcomes between the two groups.
“The increase in labour duration was moderate and clinically debatable,” said Girault.
What should clinicians be concerned about
Dr George Saade, an oncologist-gynaecologist from the University of Texas Medical Branch, Galveston, Texas, US, said “oxytocin is inexpensive but requires more monitoring.” This includes patient fluids (both intake and outtake), the frequency of uterine contractions, patient blood pressure, and heart rate of the unborn foetus.
An inappropriate dosing of oxytocin can lead to dangerous tachycardia, arrhythmias, and myocardial ischaemia. High doses can cause uterine rupture, hypertonicity, and spasms.
Clinicians prescribing oxytocin should be familiar with its side effects. When used at therapeutic doses, the drug is safe and effective.
“Overall, oxytocin is widely used and is safe for as long as careful protocols are followed,” commented Dr David Hackney from the University Hospitals Cleveland in Cleveland, Ohio, US, who is not part of the STOPOXY trial.