Prenatal anemia and postpartum hemorrhage risk: A systematic review and meta-analysis

Centre for Global Health and Division of Pediatric Global Health, Massachusetts General Hospital, Boston, Massachusetts, USA. Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA. Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA. Population Health Sciences Program, Graduate School of Arts & Sciences, Harvard University, Cambridge, MA, USA. Department of Medicine, Lagos State University Teaching Hospital, Lagos, Nigeria. Division of Maternal-Fetal Medicine, Department of Gynecology & Obstetrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.

The journal of obstetrics and gynaecology research. 2021
PICO Summary


Pregnant women with prenatal anaemia (13 studies).


Systematic review and meta-analysis to investigate the relationship between prenatal anaemia and postpartum haemorrhage (PPH) related mortality.



Severe prenatal anaemia was associated with increased PPH risk (OR = 3.54). There was no statistical association with mild (OR = 0.60), or moderate anaemia (OR = 2.09) and the risk of PPH.
INTRODUCTION Postpartum hemorrhage (PPH) has remained the leading cause of maternal mortality. While anemia is a leading contributor to maternal morbidity, molecular, cellular and anemia-induced hypoxia, clinical studies of the relationship between prenatal-anemia and PPH have reported conflicting results. Therefore, our objective was to investigate the outcomes of studies on the relationships between prenatal anemia and PPH-related mortality. MATERIALS AND METHODS Electronic databases (MEDLINE, Scopus,, PROSPERO, EMBASE, and the Cochrane Central Register of Controlled Trials) were searched for studies published before August 2019. Keywords included "anemia," "hemoglobin," "postpartum hemorrhage," and "postpartum bleeding." Only studies involving the association between anemia and PPH were included in the meta-analysis. Our primary analysis used random effects models to synthesize odds-ratios (ORs) extracted from the studies. Heterogeneity was formally assessed with the Higgins' I(2) statistics, and explored using meta-regression and subgroup analysis. RESULTS We found 13 eligible studies investigating the relationship between prenatal anemia and PPH. Our findings suggest that severe prenatal anemia increases PPH risk (OR = 3.54; 95% CI: 1.20, 10.4, p-value = 0.020). There was no statistical association with mild (OR = 0.60; 95% CI: 0.31, 1.17, p-value = 0.130), or moderate anemia (OR = 2.09; 95% CI: 0.40, 11.1, p-value = 0.390) and the risk of PPH. CONCLUSION Severe prenatal anemia is an important predictive factor of adverse outcomes, warranting intensive management during pregnancy. PROSPERO Registration Number: CRD42020149184;
Study details
Study Design : Systematic Review
Language : eng
Credits : Bibliographic data from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine