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. 2019 Feb 6;18(1):10.
doi: 10.1186/s12940-019-0450-1.

Mediating role of arsenic in the relationship between diet and pregnancy outcomes: prospective birth cohort in Bangladesh

Pi-I D Lin  1   2   3 , Sabri Bromage  4 , Md Golam Mostofa  5 , Mohammad Rahman  6 , Joseph Allen  6 , Emily Oken  7 , Molly L Kile  6   8 , David C Christiani  6   9
Affiliations

Mediating role of arsenic in the relationship between diet and pregnancy outcomes: prospective birth cohort in Bangladesh

Pi-I D Lin et al. Environ Health. .

Abstract

Background: Epidemiological evidence suggests that arsenic (As) exposure during pregnancy may reduce infant birth weight. One significant source of As exposure is diet; thus, As may indirectly affect infant growth by mediating the effect of maternal diet on birth weight (BW). This study evaluated the potential mediating effect of As in the relationship between maternal diet and BW, gestational age (GA), and gestational weight gain (GWG).

Method: The study used a prospective birth cohort in Bangladesh that captured the dietary habits of 1057 pregnant women through validated semi-quantitative food frequency questionnaires. We applied a causal mediation model with counterfactual approach and performed analyses with and without adjustment for total energy intake. Other potential confounders captured by self-report questionnaire were exposure to secondhand tobacco smoke, betel nut chewing, maternal age, education level, household income level, physical activity level during pregnancy, and daily hours spent cooking over open fire.

Result: No association was found between maternal toenail As and BW. Higher absolute and energy-adjusted protein, fat and fiber intakes were associated with higher toenail As and lower GA and GWG, while higher absolute and energy-adjusted carbohydrate intake was associated with lower toenail As and greater GA and GWG. Mediation analysis showed significant natural indirect effects by toenail As in the relationships between absolute fat, carbohydrate and fiber intake with GA. Specifically, 3% (95% CI: 1-6%) of the association between carbohydrate intake and GA was mediated by change in toenail As, 6% (95% CI: 1-9%) for absolute fat intake and 10% (95% CI: 4-13%) for absolute fiber intake. After adjusting for total energy, no significant mediating effect was observed, suggesting the mediating effect might be due to measurement error or that absolute amount of As exposure rather than the amount in relationship to total energy intake was a more important factor to consider when understanding the negative implication of As on fetal growth.

Conclusion: The mediating effect of As in the relationship between maternal diet and birth outcome was small and might be due to measurement error.

Keywords: Arsenic exposure; Fetal growth; Food frequency questionnaire; Maternal diet; Mediation analysis; Preterm birth; Rural Bangladesh; birth weight; gestational age at birth; gestational weight gain.

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Conflict of interest statement

Ethics approval and consent to participate

This study was conducted according to the guidelines of the Declaration of Helsinki, and all procedures involving human subjects/patients were approved by the Dhaka Community Hospital and Harvard T.H. Chan School of Public Health (IRB number P11351, approved February 2008). Written informed consent was obtained from all participants.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1
Fig. 1
Study flowchart
Fig. 2
Fig. 2
Simple conceptual model for mediation analysis in the context of the present study
See this image and copyright information in PMC

References

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