Research on Oxytocin Stimulation and Caesarean Section Rates

According to recent research reports published in the British Medical Journal, in a setting where monitoring of the fetal condition and the uterine contractions can be guaranteed, routine discontinuation of oxytocin stimulation may lead to a small increase in caesarean section rate but a significantly reduced risk of uterine hyperstimulation and abnormal fetal heart rate patterns.

There has been a recent surge in pregnant women who have their labour induced. This often includes stimulation with oxytocin. The stimulation requires a delicate balance between the wish for progression of labour and the risks to the fetus and mother of uterine hyperstimulation, defined as more than five contractions in 10 minutes in response to oxytocin. Different approaches to oxytocin administration have been suggested, such as:

• Pulsatile or intermittent administration
• An automatic feedback system
• High versus low dose
• Discontinuation of the stimulation when the active phase of labour is reached

Researchers undertook the current study to determine whether discontinuing oxytocin stimulation in the active phase of induced labour is associated with lower caesarean section rates.

Study Design

The study was designed as an international multicentre, double-blind, randomised controlled trial with nine hospitals in Denmark and one in the Netherlands between 8 April 2016 and 30 June 2020. Participants were 1200 women stimulated with intravenous oxytocin infusion during the latent phase of induced labour. Women were randomly assigned to have their oxytocin stimulation discontinued or continued in the active phase of labour. The main outcome measured was delivery by caesarean section.

Data Analysis

Data analysis revealed some interesting facts:

• A total of 607 women were assigned to discontinuation and 593 to continuation of the oxytocin infusion. The rates of caesarean section were 16.6% (n=101) in the discontinued group and 14.2% (n=84) in the continued group (relative risk 1.17, 95% confidence interval 0.90 to 1.53).
• In 94 parous women with no previous caesarean section, the caesarean section rate was 7.5% (11/147) in the discontinued group and 0.6% (1/155) in the continued group (relative risk 11.6, 1.15 to 88.7).
• Discontinuation was associated with longer duration of labour (median from randomisation to delivery 282 vs 201 min; P<0.001), a reduced risk of hyperstimulation (20/546 (3.7%) vs 70/541 (12.9%); P<0.001), and a reduced risk of fetal heart rate abnormalities (153/548 (27.9%) vs 219/537 (40.8%); P<0.001) but rates of other adverse maternal and neonatal outcomes were similar between groups.

Conclusion

The researchers concluded that in settings where monitoring of the fetal condition and the uterine contractions can be guaranteed, routine discontinuation of oxytocin stimulation may lead to a small increase in caesarean section rate but a significantly reduced risk of uterine hyperstimulation and abnormal fetal heart rate patterns.

For the full article, follow the link: doi: https://doi.org/10.1136/bmj.n716

Primary source: BMJ