U-Shaped Association between Maternal Hemoglobin and Low Birth Weight in Rural Bangladesh

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  • 1 Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia;
  • | 2 The International Center for Diarrhoeal Disease and Research, Dhaka, Bangladesh;
  • | 3 The University of Sydney School of Public Health, Sydney, Australia;
  • | 4 Department of Public Health Sciences, University of Virginia, Charlottesville, Virginia;
  • | 5 RTI International, Research Triangle Park, North Carolina

Low birth weight (LBW) is associated with a higher risk of neonatal mortality and the development of adult-onset chronic disease. Understanding the ongoing contribution of maternal hemoglobin (Hgb) levels to the incidence of LBW in South Asia is crucial to achieve the World Health Assembly global nutrition target of a 30% reduction in LBW by 2025. We enrolled pregnant women from the rural Tangail District of Bangladesh in a Maternal Newborn Health Registry established under The Global Network for Women’s and Children’s Health Research. We measured the Hgb of pregnant women at enrollment and birth weights of all infants born after 20 weeks gestation. Using logistic regression to adjust for multiple potential confounders, we estimated the association between maternal Hgb and the risk of LBW. We obtained Hgb measurements and birth weights from 1,665 mother–child dyads between July 2019 and April 2020. Using trimester-specific cutoffs for anemia, 48.3% of the women were anemic and the mean (±SD) Hgb level was 10.6 (±1.24) g/dL. We identified a U-shaped relationship where the highest risk of LBW was seen at very low (< 7.0 g/dL, OR = 2.00, 95% CI = 0.43–7.01, P = 0.31) and high (> 13.0 g/dL, OR = 2.17, 95% CI = 1.01–4.38, P = 0.036) Hgb levels. The mechanisms underlying this U-shaped association may include decreased plasma expansion during pregnancy and/or iron dysregulation resulting in placental disease. Further research is needed to explain the observed U-shaped relationship, to guide iron supplementation in pregnancy and to minimize the risk of LBW outcomes.

Author Notes

Address correspondence to William Petri, Division of Infectious Diseases and International Health, University of Virginia School of Medicine, 345 Crispell Drive, Charlottesville VA 22908-1340. E-mail: wap3g@virginia.edu

Disclosure: Ethics approval and consent to participate: This study was reviewed and approved by ethics review committees at the International Center for Diarrhoeal Disease and Research, Dhaka, Bangladesh; the institutional review board at the University of Virginia; and the data coordinating center at the RTI International. All women provided informed consent for participation in the study, including data collection and the follow-up visits.

Financial support: Publication of this supplement is funded by a grant to W. P. from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (U10HD076457, U10HD078438, and U01HD040636) and the National Center for Advancing Translational Science of the National Institutes of Health Award (UL1TR003015).

Authors’ addresses: Rebecca Carpenter and William Petri, Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, VA, E-mails: rmc4bc@virginia.edu and wap3g@virginia.edu. Masum Billah, The University of Sydney School of Public Health, Sydney, Australia, E-mail: billah@icddrb.org. Genevieve Lyons, Department of Public Health Sciences, University of Virginia, Charlottesville, VA, E-mail: gl2b@virginia.edu. Md Shahjahan Siraj, Qazi Rahman, and Rashidul Haque, The International Center for Diarrhoeal Disease and Research, Dhaka, Bangladesh, E-mails: shahjahan.siraj@icddrb.org, qsrahman@icddrb.org, and rhaque@icddrb.org. Vanessa Thorsten and Elizabeth McClure, RTI International, Research Triangle Park, NC, E-mails: vthorsten@rti.org and mcclure@rti.org.

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