Grotegut, C. A., Paglia, M. J., Johnson, L. N., Thames, B., & James, A. H. (2011). Oxytocin exposure during labor among women with postpartum hemorrhage secondary to uterine atony. American journal of obstetrics and gynecology. https://doi.org/10.1016/j.ajog.2010.08.023
Grotegut CA, Paglia MJ, Johnson LN, Thames B, James AH. Oxytocin exposure during labor among women with postpartum hemorrhage secondary to uterine atony. American journal of obstetrics and gynecology. 2011. doi:10.1016/j.ajog.2010.08.023
Grotegut, Chad A., et al. "Oxytocin exposure during labor among women with postpartum hemorrhage secondary to uterine atony." American journal of obstetrics and gynecology, 2011.
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RRM Academy Synopsis
Severe atony hemorrhage after birth was linked to more labor oxytocin
In a case-control study, women with severe hemorrhage from uterine atony had received significantly more oxytocin in labor. Atony means the uterus fails to tighten after birth. The study matched 54 such women with 54 controls. Oxytocin exposure still predicted severe hemorrhage after six other factors were controlled.
Key Findings
Of 12,476 deliveries from 2000 to 2004, 671 (5.4%) had a postpartum hemorrhage diagnosis and 109 needed a transfusion. Uterine atony was the primary cause in 54 (50%) of those 109.
Total oxytocin exposure, calculated as the area under the dose curve over labor, was significantly higher in women with severe hemorrhage from atony than in matched controls (p<0.001).
Oxytocin was started a mean of 684 minutes before delivery in cases and 330 minutes in controls (p<0.001). Total infusion time averaged 628 minutes in cases and 294 minutes in controls (p<0.001).
Estimated blood loss averaged 1199 ml in cases and 517 ml in controls (p<0.001). Maximal oxytocin dose during labor was also higher in cases (p<0.001).
A logistic regression model adjusted for race, body mass index, admission hematocrit, induction status, magnesium therapy, and chorioamnionitis still found that oxytocin exposure predicted severe hemorrhage.
Interpretation
The study is a retrospective case-control study built from medical records. Cases were women whose uterus failed to contract after birth and who needed a transfusion for severe bleeding. Each case had a control matched for age, parity and mode of delivery. The authors describe oxytocin exposure as an independent risk factor for severe hemorrhage from atony. They propose that prolonged treatment desensitizes the oxytocin receptor, which interferes with uterine contraction. They note that cases came from diagnosis codes and that the study relied on accurate records.
RRM Context
Restorative reproductive medicine works with the body's own functions. Oxytocin is a hormone the body makes. The authors propose that prolonged oxytocin treatment desensitizes its receptor. They write that protocols using less oxytocin may lower the rate of hemorrhage from uterine atony. They cite two protocols that cut oxytocin exposure late in labor.
Our editorial summary of this paper, not the article's abstract.
Abstract
Objective
We sought to determine if women with severe postpartum hemorrhage (PPH) secondary to uterine atony received greater amounts of oxytocin during labor compared to women without PPH.
Study Design
Subjects with severe PPH secondary to uterine atony, who received a blood transfusion, were compared to matched controls. Total oxytocin exposure was calculated as the area under the concentration curve (mU/min*min). Variables were compared using paired t test, χ², and logistic regression.
Results
Women with severe PPH had a mean oxytocin area under the curve of 10,054 mU compared to 3762 mU in controls (P < .001). After controlling for race, body mass index, admission hematocrit, induction status, magnesium therapy, and chorioamnionitis using logistic regression, oxytocin area under the curve continued to predict severe PPH.
Conclusion
Women with severe PPH secondary to uterine atony were exposed to significantly more oxytocin during labor compared to matched controls.
