Identifying a Window of Vulnerability during Fetal Development in a Maternal Iron Restriction Model Camelia Mihaila1, Jordan Schramm2, Frederick G. Strathmann1¤, Dawn L. Lee4, Robert M. Gelein5, Anne E. Luebke2,3*., Margot Mayer-Pro¨ schel1,2*. 1 Department of Biomedical Genetics, University of Rochester, Rochester, New York, United States of America, 2 Department of Neurobiology and Anatomy, University of Rochester, Rochester, New York, United States of America, 3 Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States of America, 4 Department of Pathology and Laboratory Medicine, University of Rochester, Rochester, New York, United States of America, 5 Department of Environmental Medicine, University of Rochester, Rochester, New York, United States of America Abstract It is well acknowledged from observations in humans that iron deficiency during pregnancy can be associated with a number of developmental problems in the newborn and developing child. Due to the obvious limitations of human studies, the stage during gestation at which maternal iron deficiency causes an apparent impairment in the offspring remains elusive. In order to begin to understand the time window(s) during pregnancy that is/are especially susceptible to suboptimal iron levels, which may result in negative effects on the development of the fetus, we developed a rat model in which we were able to manipulate and monitor the dietary iron intake during specific stages of pregnancy and analyzed the developing fetuses. We established four different dietary-feeding protocols that were designed to render the fetuses iron deficient at different gestational stages. Based on a functional analysis that employed Auditory Brainstem Response measurements, we found that maternal iron restriction initiated prior to conception and during the first trimester were associated with profound changes in the developing fetus compared to iron restriction initiated later in pregnancy. We also showed that the presence of iron deficiency anemia, low body weight, and changes in core body temperature were not defining factors in the establishment of neural impairment in the rodent offspring. Our data may have significant relevance for understanding the impact of suboptimal iron levels during pregnancy not only on the mother but also on the developing fetus and hence might lead to a more informed timing of iron supplementation during pregnancy. Citation: Mihaila C, Schramm J, Strathmann FG, Lee DL, Gelein RM, et al. (2011) Identifying a Window of Vulnerability during Fetal Development in a Maternal Iron Restriction Model. PLoS ONE 6(3): e17483. doi:10.1371/journal.pone.0017483 Editor: Thomas Burne, University of Queensland, Australia Received July 28, 2010; Accepted February 7, 2011; Published March 15, 2011 Copyright: 2011 Mihaila et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The work was funded by the NIH grants R01HD059739 and NIH R01NS39511, and was in part supported by the Environment Health Science Center (EHSC) at the University of Rochester. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: Margot_Mayer-Proschel@urmc.rochester.edu (MM-P); Anne_Luebke@urmc.rochester.edu (AEL) . These authors contributed equally to this work. ¤ Current address: Department of Laboratory Medicine at the University of Washington, Seattle, Washington, United States of America Introduction The clinical importance and prevalence of iron deficiency (ID) make the understanding of this micronutrient deficiency an important challenge for both the scientific and medical commu- nities. Iron is an essential micronutrient and ID affects more than 2 billion people around the world. ID occurs in many forms ranging from marginal tissue iron depletion to the most severe form of iron deficiency anemia (IDA). It has been estimated that, globally, 50% of anemia can be attributed to ID. IDA ranks at number 9 among 26 mortality risk factors and accounts for over 800,000 deaths and 35 million disability-adjusted lost life years [1]. North America alone bears 1.4% of the global burden of ID and IDA and it has been estimated that 35–58% of healthy women show some degree of ID, with a higher prevalence during pregnancy [1,2,3,4,5]. This high prevalence of ID during pregnancy seems at odds with the practice of routine iron supplementation as part of the prenatal care provided in most developed countries. Factors that contribute to the still high prevalence are complex and include concerns of early iron supplementation generating oxidative stress [6], a low compliance rate (50%) of taking iron supplements even with optimal motivation and guidance due to the undesirable adverse effects [7,8,9], and a rise in risk factors like type-2 diabetes and obesity that can cause ID and IDA despite adequate food intake [10,11,12,13]. ID and untreated IDA during pregnancy have many negative consequences for the offspring and have been shown to be associated with a higher incidence of low birth weight and prematurity [14,15,16,17,18], long-term cognitive abnormalities such as language learning impairments and behavioral changes [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35], alteration in thermoregulation [36], changes in lipid metabolism [37], stroke and seizures [38,39], altered motor function and coordination [40,41,42], and in many cases alteration of Auditory Brainstem Responses (ABRs, [35,43,44,45,46], a measure of nerve impulse conduction in the auditory system). Gestational ID also has been shown to change iron homeostasis in the offspring resulting in increased risk of developing ID later in life despite adequate nutrition [47,48,49]. It is alarming that the reported prevalence of PLoS ONE | www.plosone.org 1 March 2011 | Volume 6 | Issue 3 | e17483