Melbourne researchers have found that one of two common methods to induce labour is safer for babies, although both were as safe for the mother and neither led to more caesarean births.
The findings could help inform the growing number of inductions conducted globally each year – now around 14 million – when the risks of continued pregnancy outweigh the benefits.
Published in The Lancet, the Monash Health and Monash University-led study found clear evidence that a balloon catheter leads to an improved safety profile for newborns than vaginal hormones.
This included fewer adverse events such as acidosis (a build-up of acid in the bloodstream), poor condition after birth, or neonatal intensive care unit admission. There was no difference in maternal adverse events or caesarean rates between the two methods.
Labour induction is one of the most common obstetric interventions and rates have significantly increased over the past decade, from 25 to 35 per cent in Australia alone.
Most commonly, the cervix is ‘ripened’ either mechanically, by inserting a water-filled balloon catheter which exerts pressure on the cervix over several hours and guides it open, or hormonally, with medications that replicate prostaglandin, a hormone which also softens and opens the cervix.
The international data meta-analysis concluded that while both methods were effective, balloon catheters were safer for newborns and using them could considerably reduce adverse birth events.
Investigators of 12 high-quality trials contributed data, resulting in 5,460 women who were randomised in original trials for either balloon catheter or vaginal prostaglandins.
First author Dr Madeleine Jones, a Monash Health/Monash Women’s Registrar and Monash University Department of Obstetrics and Gynaecology PhD candidate, said previous research had demonstrated that balloon catheters were likely as effective as vaginal prostaglandin.
“However, it was unclear if one method was safer than the other, as there is a limited ability to measure these with either single clinical trials or analysis of summary data from multiple trials,” Dr Jones said.
“We established an international collaborative that was led by our research group at Monash University and Monash Health to address this knowledge gap. This enabled us to achieve some clear and important results.”
Senior author Dr Wentao Li, a Monash University School of Clinical Sciences Department of Obstetrics and Gynaecology Research Fellow, said the results were significant.
“For the first time, we identified clear evidence that a balloon catheter over vaginal prostaglandins leads to an improved safety profile for newborns, including fewer adverse events such as acidosis, poor condition after birth, or admission to a neonatal intensive care unit,” Dr Li said.
“Maternal adverse events did not show any difference between the two methods, nor was there a significant difference in the rates of caesarean section.
“What all this means is perinatal safety should be carefully assessed in shared decision-making and policymaking around choices of labour induction methods.”
Read the full paper in The Lancet: Balloon Catheters versus Vaginal Prostaglandins for Labour Induction (CPI Collaborative): An Individual Participant Data Meta-analysis of Randomised Controlled Trials.
Induction background
In women with an unripe cervix, labour induction starts with cervical ripening, before uterine contractions can be initiated. Cervical ripening can be achieved with mechanical methods, commonly a single-balloon catheter or double-balloon catheter, or pharmacological methods, including exogenous prostaglandins such as misoprostol (PGE1) or dinoprostone (PGE2).
One in five labour inductions in women with an unripe cervix do not result in a vaginal birth, requiring Caesarean section. Induction of labour also carries the risks of rare adverse events, including maternal and neonatal morbidity and mortality. Hence, identifying the optimal method of labour induction is of enormous importance for women and babies worldwide.
