Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Jun 5.
doi: 10.1097/AOG.0000000000005956. Online ahead of print.

Postpartum Hemorrhage in Patients With a Low-Lying Placenta: A Systematic Review and Meta-analysis

Giulia Bonanni  1 , Maria C Lopez, Sofia M Tarchi, May Abiad, Camille Shantz, Elisa Bevilacqua, Scott A Shainker, Anna M Modest, Kjersti Aagaard, Vincenzo Berghella, Alireza A Shamshirsaz
Affiliations

Postpartum Hemorrhage in Patients With a Low-Lying Placenta: A Systematic Review and Meta-analysis

Giulia Bonanni et al. Obstet Gynecol. .

Abstract

Objective: We hypothesized that a second- or third-trimester diagnosis of low-lying placenta imparts underappreciated risk for postpartum hemorrhage (PPH) and placenta accreta spectrum (PAS). To quantify this risk and to assess whether it varies by the specific distance of the placenta from the cervical os and low-lying placenta resolution status, we conducted a systematic review and meta-analysis.

Data sources: Systematic searches were conducted in PubMed, ClinicalTrials.gov, EMBASE, and Web of Science from database inception to April 30, 2024.

Methods of study selection: A total of 3,700 results were screened for relevance with the PICO framework: population-singleton pregnancies; intervention-low-lying placenta; comparators-normal placentation; and outcomes-PPH and PAS. Studies published before 2000 were excluded to minimize bias from ultrasound sensitivity.

Tabulation, integration, and results: Twenty-one studies (3,704 patients with low-lying placenta, 2,555 with normal placentation) were included. Data extraction and quality assessment with the Newcastle-Ottawa Scale were performed independently by three reviewers. At any gestational age, low-lying placenta imparted a significant PPH risk (risk ratio [RR] 2.10, 95% CI, 1.02-4.35, P=.05, I2=0.0%) compared with non-low-lying placenta. The incidence of PPH was 16.0% (95% CI, 10.3-24.1%, I2=93.3%) in low-lying placenta 1-20 mm compared with 5.8% (95% CI, 3.8-8.8%, I2=79.9%) in non-low-lying placenta. When parsed by clinically meaningfully strata, a high incidence of PPH persisted with resolved low-lying placenta (resolved: 8%, 95% CI, 4.1-16.3%, I2=85.0%; unresolved: 29.2%, 95% CI, 19.0-42.0%, I2=70.5%; non-low-lying placenta: 5.8%, 95% CI, 3.8-8.8%, I2=79.9%) with no difference in PPH risk at less than 2 cm from the os (low-lying placenta 1-10 mm: 16.6%, 95% CI, 9.2-28.3%, I2=78.4%; low-lying placenta 11-20 mm: 17.5%, 95% CI, 8.8-31.7%, I2=92.2%; RR 0.97, 95% CI, 0.67-1.41, P=.84, I2=0.0%). An important finding is that PAS disorders affected 9.0% (95% CI, 4.7-16.8%, I2=89.9%) of all low-lying placenta cases.

Conclusion: Antepartum diagnosis of low-lying placenta is associated with a twofold increased risk of PPH compared with normal placentation. The pooled proportions of PPH were 16.6% in the 1-10 mm group and 17.5% in the 11-20 mm low-lying placenta group, with no significant difference. This meta-analysis is the first to quantify the risk of PPH associated with low-lying placenta, emphasizing the need for rigorous monitoring and delivery management of pregnancies with low-lying placenta to mitigate the burden of PPH on maternal morbidity.

Systematic review registration: PROSPERO, CRD42024558043.

PubMed Disclaimer

Conflict of interest statement

Financial Disclosure Scott A. Shainker received payment for serving on the Roche Pharmaceutical and Diagnostic Advisory Board. His institution received payment from the Chase Koch Foundation and Oxford University Press. Anna M. Modest received payment for ABC Board Review. The other authors did not report any potential conflicts of interest.

References

    1. Reddy UM, Abuhamad AZ, Levine D, Saade GR; Fetal Imaging Workshop Invited Participants. Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging Workshop. Am J Obstet Gynecol 2014;210:387–97. doi: 10.1016/j.ajog.2014.02.028 - DOI
    1. Jansen C, De Mooij Y, Blomaard C, Derks JB, van Leeuwen E, Limpens J, et al. Vaginal delivery in women with a low‐lying placenta: a systematic review and meta-analysis. BJOG 2019;126:1118–26. doi: 10.1111/1471-0528.15622 - DOI
    1. Ornaghi S, Tessitore IV, Vergani P. 372: Placental edge to internal os distance and mode of delivery in low-lying placentas. Am J Obstet Gynecol 2019;220:S256. doi: 10.1016/j.ajog.2018.11.393 - DOI
    1. Jansen CHJR, Kleinrouweler CE, Van Leeuwen L, Ruiter L, Limpens J, van Wely M, et al. Final outcome of a second trimester low-positioned placenta: a systematic review and meta-analysis. Eur J Obstet Gynecol Reprod Biol 2019;240:197–204. doi: 10.1016/j.ejogrb.2019.06.020 - DOI
    1. Ornaghi S, Colciago E, Vaglio Tessitore I, Abbamondi A, Antolini L, Locatelli A, et al. Mode of birth in women with low-lying placenta: protocol for a prospective multicentre 1:3 matched case-control study in Italy (the MODEL-PLACENTA study). BMJ Open 2021;11:e052510. doi: 10.1136/bmjopen-2021-052510 - DOI

LinkOut - more resources