Study finds use of labour-augmenting drug for extended time may contribute to reduced effect in controlling postpartum bleeding

August 21, 2013 – In a new study published today in the September issue of Anesthesiology, Dr. Mrinalini Balki and her colleagues found that the use of oxytocin, a drug commonly used to speed up or induce labour, may increase a woman's chances of postpartum bleeding.

Women are commonly given oxytocin during labour to advance or induce labour and all women are given oxytocin post-delivery in order to reduce post-partum bleeding. Post-partum bleeding can be a significant risk to women and can lead to post-partum hemorrhage, which affects approximately 15% of cesarean births and 5% of vaginal births.

This study, which builds on previous work done by Dr. Balki on the use of oxytocin during and post-delivery, looked at samples of uterine muscle from women who had elected cesarean deliveries and were treated with different doses of oxytocin for two, four, six and 12 hours.

The researchers noted how the strength and frequency of contractions was impacted by additional doses of oxytocin and found that increasing the dose and duration of oxytocin treatment from two to 12 hours significantly reduced the strength of the contractions.

“While oxytocin helps to move labor along, after prolonged use, the mother becomes desensitized to it," said Dr. Mrinalini Balki, staff anesthesiologist at Mount Sinai Hospital and Associate Professor at the University of Toronto. “This research provides insight into re-examining the choice and dose of medications used to contract the uterus post-delivery. Based on our results, anesthesiologists may need to use higher doses of oxytocin after cesarean deliveries in women with oxytocin augmented labors, or may need to resort to different medications to controlling uterine bleeding. However, further clinical studies are warranted to confirm these findings.”