Effects of hemoglobin levels during pregnancy on adverse maternal and infant outcomes: a systematic review and meta-analysis

Jenny Jung, Md Mizanur Rahman*, Md Shafiur Rahman, Khin Thet Swe, Md Rashedul Islam, Md Obaidur Rahman, Shamima Akter

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

67 Citations (Scopus)


Maternal anemia affects approximately 56 million women worldwide and increases the risk of adverse pregnancy outcomes. Our study aimed to summarize the evidence for the association between maternal hemoglobin (Hb) concentrations and maternal or infant outcomes, evaluating it in a continuous manner. In this systematic review and meta-analysis, we conducted an electronic search on PubMed, Embase, CINAHL, and Web of Science from inception to April 19, 2017, and further updated to November 21, 2018, applying subject heading terms related to pregnant women with anemia. We included 117 studies with 4,127,430 pregnancies. Maternal anemia increased the risk of low birth weight (odds ratio (OR), 1.65; 95% confidence interval (CI): 1.45−1.87), preterm birth (PTB) (OR, 2.11; 95% CI: 1.76–2.53), perinatal mortality (PNM) (OR, 3.01; 95% CI: 1.92−4.73), stillbirth (OR, 1.95; 95% CI: 1.15−3.31), and maternal mortality (OR, 3.20; 95% CI: 1.16−8.85). A nonlinear relationship was found between maternal Hb and adverse maternal and infant outcomes. The OR of outcomes such as PTB, small-for-gestational age, PNM, preeclampsia, gestational hypertension, and postpartum hemorrhage was increased by two to three times. Assessing Hb as a continuous variable is important to determine the associated risk of adverse outcomes with decreasing or increasing levels.

Original languageEnglish
JournalAnnals of the New York Academy of Sciences
Publication statusAccepted/In press - Jan 1 2019


  • anemia
  • dose−response analysis
  • hemoglobin concentration
  • infant outcomes
  • random-effects meta-analysis

ASJC Scopus subject areas

  • Neuroscience(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • History and Philosophy of Science


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