Poster Session 1
Category: Labor
Poster Session 1
Rachel L. Bank, MD (she/her/hers)
OB/GYN Resident, PGY-2
Department of Women’s Health, Dell Medical School at the University of Texas at Austin
Austin, Texas, United States
Miriam J. Alvarez, PhD
Research Scientist
Department of Women’s Health, Dell Medical School at the University of Texas at Austin
Austin, Texas, United States
Sindhu K. Srinivas, MD, MSCE (she/her/hers)
Professor of Obstetrics and Gynecology/Maternal Fetal Medicine
Department of Obstetrics and Gynecology, Perelman School of Medicine, Pregnancy & Perinatal Research Center
Philadelphia, Pennsylvania, United States
Aaron B. Caughey, MD, PhD
Chair and Professor of Obstetrics and Gynecology
Oregon Health & Science University
Oregon Health & Science University, Oregon, United States
Alan T. Tita, MD, MPH, PhD (he/him/his)
Assoc. Dean for Global & Women’s Health; Chair & Director, Mary Heersink Inst. of Global Health
Center for Research in Women’s Health, University of Alabama at Birmingham
Birmingham, Alabama, United States
Methodius G. Tuuli, MBA, MD, MPH
Chace-Joukowsky Professor of Obstetrics and Gynecology, Chair of Obstetrics and Gynecology
Department of Obstetrics and Gynecology, Warren Alpert Medical School at Brown University, and Women & Infants Hospital of Rhode Island
Providence, Rhode Island, United States
George A. A. Macones, MD, MS, MSCE
Chair & Professor, Department of Women’s Health
Department of Women’s Health, Dell Medical School at the University of Texas at Austin
Austin, Texas, United States
Alison G. G. Cahill, MD, MSCI
Assoc. Dean, Translational Research; Prof, Women’s Health; Dir, Health Transformation Research Inst.
Department of Women’s Health, Dell Medical School at the University of Texas at Austin
Department of Women’s Health, Dell Medical School at the University of Texas at Austin, Texas, United States
Oxytocin is commonly used for labor induction or augmentation, but the effect of latent phase exposure on postpartum hemorrhage is not known. We sought to evaluate the association between latent phase oxytocin exposure and postpartum bleeding outcomes.
Study Design:
Secondary analysis of a multicenter randomized controlled trial of nulliparous women with term singleton pregnancies comparing immediate vs. delayed pushing in the second stage of labor. In this study, the primary exposure was oxytocin dose, categorized as no, low, or high based on maximum dose (≥20 mU/min). Exclusions were incomplete data or outlier values. The primary outcome was postpartum hemorrhage (PPH), defined as estimated blood loss >500 mL (vaginal) or >1000 mL (cesarean). Secondary outcomes were the use of additional uterotonics, blood transfusion, and a composite. Log-binomial regression was used to estimate risk ratios (RRs) and 95% confidence intervals (CIs). Adjusted models controlled for induction, timing of maximum dose (latent vs active phase), and prolonged first stage ( >95th percentile).
Results:
Among 2,404 patients in the parent trial, 1,495 patients were included. High-dose oxytocin was associated with a significantly increased risk of PPH (aRR = 2.2; 95% CI: 1.2–3.8; p = 0.01) and the composite outcome (aRR = 2.1; 95% CI: 1.2–3.6; p = 0.01) when compared to no exposure; high-dose exposure was associated with a non-significant increase in additional uterotonic use (aRR = 2.5; 95% CI: 0.9–7.1; p = 0.08). Low-dose exposure was not associated with increased risk for any outcome. A similar pattern of results was observed when defining PPH as estimated blood loss >1000 mL and when adjusting for latent phase duration rather than prolonged first stage. Risk ratios for transfusion were not calculated due to low event counts.
Conclusion:
High-dose latent phase oxytocin exposure was associated with an increased risk of postpartum hemorrhage and composite maternal blood loss complications when compared to no exposure. Current PPH risk scoring systems do not include high latent phase oxytocin exposure, but perhaps they should.