Aflatoxin Exposure During Pregnancy, Maternal Anemia, and Adverse Birth Outcomes.

Laura E Smith,Jean H Humphrey,Andrew J Prendergast,Rebecca J Stoltzfus,Paul C Turner

doi:10.4269/ajtmh.16-0730

Abstract

Pregnant women and their developing fetuses are vulnerable to multiple environmental insults, including exposure to aflatoxin, a mycotoxin that may contaminate as much as 25% of the world food supply. We reviewed and integrated findings from studies of aflatoxin exposure during pregnancy and evaluated potential links to adverse pregnancy outcomes. We identified 27 studies (10 human cross-sectional studies and 17 animal studies) assessing the relationship between aflatoxin exposure and adverse birth outcomes or anemia. Findings suggest that aflatoxin exposure during pregnancy may impair fetal growth. Only one human study investigated aflatoxin exposure and prematurity, and no studies investigated its relationship with pregnancy loss, but animal studies suggest aflatoxin exposure may increase risk for prematurity and pregnancy loss. The fetus could be affected by maternal aflatoxin exposure through direct toxicity as well as indirect toxicity, via maternal systemic inflammation, impaired placental growth, or elevation of placental cytokines. The cytotoxic and systemic effects of aflatoxin could plausibly mediate maternal anemia, intrauterine growth restriction, fetal loss, and preterm birth. Given the widespread exposure to this toxin in developing countries, longitudinal studies in pregnant women are needed to provide stronger evidence for the role of aflatoxin in adverse pregnancy outcomes, and to explore biological mechanisms. Potential pathways for intervention to reduce aflatoxin exposure are urgently needed, and this might reduce the global burden of stillbirth, preterm birth, and low birthweight.

Highlights

Aflatoxins are toxic secondary metabolites of Aspergillus molds that contaminate foods such as maize, rice, and legumes
We aimed to conduct a narrative review to evaluate the evidence for a potential role of aflatoxin exposure and anemia in intrauterine growth retardation, preterm birth, and pregnancy loss
Aflatoxins B1 (AFB1), B2, G1, and G2 are produced by several species of Aspergillus; AFB1 exposure is the focus of most research because it occurs most frequently and is most toxic.[27]

Summary

Introduction

Aflatoxins are toxic secondary metabolites of Aspergillus molds that contaminate foods such as maize, rice, and legumes. Around 0.5 billion people, predominantly those living in developing countries, are at significant risk of exposure to dietary aflatoxins, with many people chronically exposed to aflatoxins throughout life.[1] In many developing countries, aflatoxins are not effectively controlled in the food system and consumption of high-risk foods, such as maize and groundnuts, is common. Aflatoxin accumulation in food is highly dependent on environmental factors such as moisture, temperature, nitrogen availability, and plant density,[2] as well as poor harvest practices and improper grain storage.[3,4,5,6] Aflatoxins have been most widely studied as causative agents of liver cancer.[7] Chronic exposure has been associated with other adverse human health outcomes, including growth faltering[8] and maternal anemia.[9] Exposure during pregnancy has been widely documented,[10,11] but the effects on the mother and fetus are not well described

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