Research on Oxytocin Exposure and Obstetric Hemorrhage

Boston, MA: Prolonged exposure to intrapartum exogenous oxytocin is associated with an increased risk of obstetric hemorrhage (OBH) and increased quantitative blood loss (QBL), says research published in the journal Obstetrics & Gynecology.

There is no clear understanding of the relationship between the duration of intrapartum oxytocin exposure and OBH. The use of estimated, not quantitative, blood loss data was the limiting factor for the prior studies. Megan Alexander, Boston University School of Medicine, Boston, MA, and colleagues, therefore, aimed to assess whether the prolonged duration of intrapartum Pitocin exposure is associated with:

• Increased quantitative blood loss (QBL)
• OBH (QBL greater than or equal to 1,000 mL)
• Hemorrhage-related maternal morbidity

For this purpose, the researchers performed a retrospective cohort analysis of all who were exposed to intrapartum exogenous oxytocin for induction or augmentation from January 1, 2018, to December 31, 2019. Women were divided by hours of intrapartum oxytocin exposure: <12 hours or ≥12 hours of exposure. t-test and chi-square test were used to make comparisons between the groups.

Findings of the Study

• Of 5,332 patients, 2,232 (41.9%) had intrapartum oxytocin exposure.
• Compared to patients with intrapartum oxytocin exposure <12 hours, those with ≥12 hours had higher mean QBL and higher probability of OBH.
• Oxytocin exposure of ≥12 hours was not associated with increased hemorrhage-related morbidity.

Co-investigator Ashley Comfort of Boston Medical Center said it was significant that patients who had a longer exposure to oxytocin and went on to have a C-section did not face an increased hemorrhage risk. In the context of high rates of C-section deliveries, as well as an effort to decrease these rates, more data on the risk of obstetric interventions by mode of delivery is critical to help clinicians make informed choices.

"Prolonged exposure to oxytocin during birth, in particular >12 hours, was associated with increased QBL and increased probability of OBH," wrote the authors. "Future studies should additionally explore the impact of rate and dose of oxytocin on the risk of obstetric hemorrhage."

Reference

Alexander, Megan MS; Wang, Michelle MD; Srivastava, Akanksha BS; Tummala, Swetha P. BS; Abbas, Diana S. BS; Comfort, Ashley MD. Prolonged Duration of Oxytocin Exposure Increases Obstetric Hemorrhage Risk [A135], Obstetrics & Gynecology: May 2022 - Volume 139 - Issue - p 39S-40S doi: 10.1097/01.AOG.0000825820.92319.9e