Modifiable risk factors for anemia in pregnancy: an umbrella review of systematic reviews and meta-analyses

Abstract

BACKGROUND: Anemia during pregnancy affects more than one-third of women globally, with the heaviest burden in low- and middle-income countries. It contributes substantially to maternal morbidity, adverse birth outcomes, and increased neonatal mortality. Despite extensive research, there remains a lack of comprehensive and up-to-date synthesis on modifiable determinants to guide effective, targeted interventions. This umbrella review aimed to consolidate evidence from systematic reviews and meta-analyses on modifiable risk factors associated with anemia in pregnancy. METHODS: A systematic search was conducted across PubMed, Scopus, ScienceDirect, Epistemonikos, Hinari, Google Scholar, and the Cochrane Library. Search terms combined controlled vocabulary and free-text keywords including anemia, hemoglobin, iron deficiency, determinants, pregnant women, systematic review, and meta-analysis. Boolean operators (OR/AND) were applied, and the search was limited to English-language publications from 2014 to 2024. Eligible studies included systematic reviews and meta-analyses examining risk factors for anemia among pregnant women. Methodological quality was assessed using the Joanna Briggs Institute (JBI) critical appraisal tool, and synthesis followed JBI guidance to ensure rigor and transparency. Certainty of evidence assessed using GRADE. RESULTS: Of 13,348 records identified, 10 systematic reviews and meta-analyses were included. The synthesis highlighted several modifiable risk factors. Nutritional determinants included low dietary diversity (RR = 2.38-3.59), poor dietary practices (AOR = 1.63-2.97), and inadequate iron/folic acid supplementation (AOR = 1.38-1.82). Maternal health conditions, particularly intestinal parasite infections (AOR = 2.18-4.34) and malaria (AOR = 1.94-11.19), showed strong associations. Sociodemographic risks included low maternal education (AOR = 1.34-2.04), short birth intervals (< 24 months; AOR = 1.27-2.84), adolescent pregnancy (AOR = 2.60), large family size (AOR = 1.58-1.95), and rural residence (RR = 1.56). Limited healthcare access, especially lack of antenatal care (AOR = 1.36-2.02), further increased risk. Considerable heterogeneity (I²=0-94.5%) and low-to-moderate certainty ratings (GRADE) suggest variability across settings and highlight context dependence. CONCLUSIONS: Anemia during pregnancy arises from multiple modifiable factors, including poor nutrition, low dietary diversity, adolescent pregnancy, and infections like malaria and intestinal parasites. This umbrella review highlights the importance of developing context-specific interventions and implementing multisectoral policies that integrate nutrition and infection-control strategies to reduce the global burden of maternal anemia.