Similar time from induction of labour to delivery with low- vs high-dose oxytocin

The administration of either low- or high-dose oxytocin does not impact time from induction of labour to delivery in lean and obese women, according to a study presented at SMFM 2020.

This trial, conducted by researchers from the University of Arizona in Seattle, Washington, US, included 140 lean and obese women (≥37 weeks of gestation) undergoing induction of labour. They were randomized into four groups: lean women who received high-dose or low-dose oxytocin, and obese women who received high-dose or low-dose oxytocin (n=35 in each group). The primary endpoint of the study was the length of time to delivery (defined as minutes from induction of labour to delivery). [SMFM 2020, abstract 641]

The length of time from induction of labour to vaginal delivery was similar between women who received low- and high-dose oxytocin, be it lean women (796 vs 694 minutes; p=0.363) or obese women (715 vs 762 minutes; p=0.733).

“Obese women have longer labours and are more likely to require a Caesarean delivery. We hypothesized that high-dose oxytocin would decrease time to delivery in an obese cohort undergoing an induction of labour,” said the researchers.

The results showed no difference in time to delivery in women who received low-dose or high-dose oxytocin, regardless of whether they were obese or lean, they said.

However, a higher rate of Caesarean deliveries occurred among women who received low-dose oxytocin compared with those who received high-dose oxytocin, both among lean (14.29 percent vs 5.71 percent) and obese women (11.43 percent vs 2.86 percent).

This was in contrast to another study conducted by researchers from Ireland, presented at SMFM 2019, that reported a non-significant higher rate of Caesarean deliveries among recipients of high-dose oxytocin compared with low-dose oxytocin (37.0 percent vs 30.0 percent; p=0.108). [SMFM 2019, abstract 772]

This second study included 563 nulliparous women (vertex presentation between 39+0 and 40+6 weeks’ gestation) who had their labour induced with either high-dose (n=277) or low-dose oxytocin (n=286). As with the previous study, there was no difference in duration of labour between the low- and high-dose oxytocin groups (9.3 vs 8.6 hours; p=0.767). [SMFM 2019, abstract 772]

“Oxytocin is the most commonly used agent [for labour induction]; however, the optimum dosing regimen has yet to be reliably quantified,” said the researchers from Perinatal Ireland and Rotunda Hospital in Leinster, Dublin, Ireland.