Oxytocin · research summary

Association between oxytocin exposure in the second stage of labor and postpartum hemorrhage among nulliparous patients with neuraxial analgesia.

Pregnancy (Hoboken, N.J.) · 2026. Summary drawn from the study's full text. Each statement is followed by the exact sentence it comes from. This is a research summary, not medical advice.

Study type

Secondary analysis of a multicenter randomized controlled trial
“This study was a secondary analysis of a multicenter randomized controlled trial, Optimizing the Management of the Second Stage of Labor (OMSS) [14], which evaluated immediate versus delayed pushing strategies in the second stage of labor.”

Subjects

Term singleton nulliparous patients with neuraxial analgesia
“Nulliparous patients at or beyond 37 weeks of gestational age admitted for spontaneous or induced labor with neuraxial analgesia were eligible.”

Sample size

2302 participants
“A total of 2302 participants were included from the parent trial.”

Duration

2014 to 2017
“The trial took place from 2014 to 2017 at six United States academic and community‐based medical centers”

Reported findings

Each 100-mU increase in estimated second-stage oxytocin exposure was associated with a 2.5% higher risk of the primary maternal composite outcome and a 2.7% higher risk of postpartum hemorrhage.
“Each 100‐mU increase in estimated second‐stage oxytocin exposure was associated with a 2.5% higher risk of the primary maternal composite outcome (aRR, 1.025, 95% confidence interval [CI], 1.014–1.036; p < 0.001) and a 2.7% higher risk of PPH (aRR, 1.027, 95% CI, 1.015–1.038; p < 0.001).”
High cumulative exposure was associated with a 60% higher risk of the primary maternal composite outcome and a 63% higher risk of postpartum hemorrhage compared with no exposure.
“Categorical sensitivity analyses demonstrated similar findings, with high exposure associated with a 60% higher risk of the primary maternal composite outcome and a 63% higher risk of PPH compared with no exposure.”
Increasing exposure was associated with greater estimated blood loss.
“In exploratory analyses, increasing exposure was associated with greater EBL (aRR, 1.008, 95% CI, 1.006–1.010; p < 0.001).”

Source: PubMed 42812628 · DOI 10.1002/pmf2.70467 · all study summaries

Study type

Secondary analysis of a multicenter randomized controlled trial

“This study was a secondary analysis of a multicenter randomized controlled trial, Optimizing the Management of the Second Stage of Labor (OMSS) [14], which evaluated immediate versus delayed pushing strategies in the second stage of labor.”

Reported findings

Each 100-mU increase in estimated second-stage oxytocin exposure was associated with a 2.5% higher risk of the primary maternal composite outcome and a 2.7% higher risk of postpartum hemorrhage.

“Each 100‐mU increase in estimated second‐stage oxytocin exposure was associated with a 2.5% higher risk of the primary maternal composite outcome (aRR, 1.025, 95% confidence interval [CI], 1.014–1.036; p < 0.001) and a 2.7% higher risk of PPH (aRR, 1.027, 95% CI, 1.015–1.038; p < 0.001).”

High cumulative exposure was associated with a 60% higher risk of the primary maternal composite outcome and a 63% higher risk of postpartum hemorrhage compared with no exposure.

“Categorical sensitivity analyses demonstrated similar findings, with high exposure associated with a 60% higher risk of the primary maternal composite outcome and a 63% higher risk of PPH compared with no exposure.”

Increasing exposure was associated with greater estimated blood loss.

“In exploratory analyses, increasing exposure was associated with greater EBL (aRR, 1.008, 95% CI, 1.006–1.010; p < 0.001).”