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CME Credit Offered
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Poster Session 1

(205) Postpartum Hemorrhage Risk in patients with a Low-Lying Placenta: A Systematic Review and Meta-Analysis

Thursday, January 30, 2025
10:30 AM – 12:30 PM  

    Submitting Author and Presenting Author(s)

  • Giulia Bonanni, MD

    Postdoctoral Research Fellow
    Postdoctoral Research Fellow Fetal Care and Surgery Center Division of Fetal Medicine and Surgery Boston Children's Hospital, Harvard Medical School
    Boston, MA, United States

    • Coauthor(s)

  • ML

    Maria C. López-Girón, MD

    Facultad de Ciencias de la Salud, Universidad Icesi, Cali, Colombia
    Facultad de Ciencias de la Salud, Universidad Icesi, Cali, Colombia, Valle del Cauca, Colombia

  • ST

    Sofia Maria Tarchi

    Department of Biomedical Sciences, Humanitas University
    Milan, Lombardia, Italy

  • May Abiad, MD (she/her/hers)

    Postdoctoral Research Fellow
    Maternal Fetal Care Center, Boston Children's Hospital
    Boston, Massachusetts, United States

  • Camille Shantz, BA

    Johns Hopkins University
    Baltmore, Maryland, United States

  • EB

    Elisa Bevilacqua, MD, PhD

    Department of Women, Children, and Public Health Sciences, IRCCS Agostino Gemelli University Polyclinic Foundation, Catholic University of the Sacred Heart
    Rome, Lazio, Italy

  • Kjersti M. Aagaard, MD, PhD

    Medical Director, HCA Healthcare and HCA Research Institute
    Boston Children’s Hospital, Division of Fetal Medicine and Surgery, Boston, MA; HCA Healthcare and HCA Healthcare Research Institute, Nashville, TN; HCA Texas Maternal Fetal Medicine, Houston, TX; Baylor College of Medicine and Texas Children's Hospital, Houston, TX
    Tomball, Texas, United States

  • Vincenzo Berghella, MD (he/him/his)

    Professor, Director
    Sidney Kimmel Medical College of Thomas Jefferson University
    Philadelphia, Pennsylvania, United States

  • Alireza A. Shamshirsaz, MD (he/him/his)

    Department Director, Professor of Surgery
    Fetal Surgeon Chief, Division of Fetal Medicine and Surgery Director of the Maternal Fetal Care Center Director of the Perinatal Surgery Fellowship Professor of Surgery, Boston Children’s Hospital Harvard Medical School
    Boston, Massachusetts, United States

Objective: Postpartum hemorrhage (PPH) is a major cause of maternal morbidity and mortality. We hypothesized that low-lying placenta (LLP) imparts underappreciated risk for PPH. We conducted a systematic review and meta-analysis to quantify the PPH risk accompanying an antepartum diagnosis of LLP.

Study Design: We systematically searched PubMed, Embase, and Web of Science (inception - 4/30/2024) and included RCTs, prospective and case-control studies per PICO framework: Population - singleton pregnancies; Intervention - low-lying placenta; Comparators - normal placentation (non-LLP); Outcomes - PPH and Placenta Accreta Spectrum (PAS) disorders (Fig.1A). Subgroup analyses by cervical os distance and resolution status were conducted. The Newcastle-Ottawa Scale was used to assess study quality. Risk Ratios (RRs) and pooled proportions were computed using R. PROSPERO registration: CRD42024558043.

Results: We included 21 studies (n = 3,704 LLP, n= 2,555 normal placenta). Antepartum diagnosis of LLP, at any gestational age, imparted a significant PPH risk (RR 2.10, 95% CI 1.02-4.35, p=0.0477, I2 = 0%; Fig.1B). PPH incidence was 15% (95% CI 10-22%, I2 = 93%) in LLP versus 6% (95% CI 4-9%, I2 = 83%) in non-LLP. When parsed by clinically meaningfully strata, significant risk of PPH persisted with resolved LLP (resolved 8%, 95% CI 4-16%, I2 = 85% vs unresolved 29%, 95% CI 19-42%, I2 = 71%; Fig.1B) with no difference in PPH risk at under 2cm from the os (LLP 1-10 mm vs 10-20 mm; RR 0.97, 95% CI 0.67-1.41, p=0.84, I2 = 0%; Fig.1C, D). Importantly, PAS disorders affected 9% (95% CI 5-17%, I2 = 89%) of all LLP cases.

Conclusion: Antepartum diagnosis of LLP, including presumptively resolved cases, is associated with a twofold increased risk of PPH when compared to pregnancies without LLP. This is the first meta-analysis to reliably quantify the risk of LLP, emphasizing a previously underrecognized role of rigorous monitoring and delivery management of pregnancies with LLP in reducing the burden of PPH on maternal morbidity.