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Background Prenatal exposure to heavy metals has been linked to a variety of adverse outcomes in newborn health and later life. Toxic metals such as cadmium (Cd), manganese (Mn) and lead (Pb) have been implicated to negatively affect newborn neurobehavior. Placental levels of these metals may provide additional understandings on the link between prenatal toxic metal exposures and neurobehavioral performances in newborns. Objective To evaluate associations between placental concentrations of toxic metals and newborn neurobehavioral performance indicated through the NICU Network Neurobehavioral Scales (NNNS) latent profiles. Method In the Rhode Island Child Health Study cohort (n = 625), newborn neurobehavioral performance was assessed with NNNS, and a latent profile analysis was used to define five discrete neurobehavioral profiles based on summary scales. Using multinomial logistic regression, we determined whether increased levels of placental toxic metals Cd, Mn and Pb associated with newborns assigned to the profile demonstrating atypical neurobehavioral performances. Results Every doubling in placenta Cd concentration was associated with increased odds of newborns belonging to the atypical neurobehavior profile (OR: 2.72, 95% CI [1.09, 6.79]). Detectable placental Pb also demonstrated an increased odds of newborns assignment to the atypical profile (OR: 3.71, 95% CI [0.97, 13.96]) compared to being in the typical neurobehavioral profile. Conclusions Toxic metals Cd and Pb measured in placental tissue may adversely impact newborn neurobehavior. Utilizing the placenta as a prenatal toxic metal exposure biomarker is useful in elucidating the associated impacts of toxic metals on newborn health.

Background The placenta is responsible for the exchange of nutrients and for preventing harmful compounds from entering the fetal circulation. With increasing industrialization, exposures to commercial and toxic metals become a concern for both pregnant women and those planning a pregnancy. The understanding of transport mechanisms and pharmacokinetics for most inorganic elements is incomplete and limited to normal term deliveries. Objectives To obtain novel data on 46 inorganic elements in placentae from two high-risk obstetric populations, women carrying multiples and adolescents carrying singletons, evaluating differences, if present, and identifying predictors of placental content. Methods Placental tissue was collected from adolescents carrying singletons and adults carrying multiples. Elemental content was analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). Multivariate regression and factor analyses were used. Results With the exception of Au and Pt, almost all placentae contained quantifiable concentrations of each element analyzed. All placentae contained the essential elements Ca, Fe, Mg, Se and Zn, which clustered together onto the same factor. Most elements were higher in placentae from women carrying multiples. Differences in placental content disappeared after adjusting for maternal age. Rare earth elements (REEs) clustered together and remained higher in the multiples even after adjusting for maternal age. Conclusion Human placentae contain a wide range of elements, including REEs. Ranges differed considerably between cohorts. Elements with similar chemical properties, like REEs or nutritionally essential elements, clustered together. Maternal age, and therefore longer environmental exposure, was significantly associated with elevated element concentrations in the placenta. Placental concentrations of several metals that are known to be nutritionally essential (e.g., Fe, Ca, Mg, and Zn) did not differ significantly between cohorts, suggesting tight regulation, whereas concentrations of environmental contaminants differed significantly between groups, even after adjusting for maternal age.

Manganese (Mn) is both an essential element and a potent neurotoxin. Higher demand during pregnancy leads to increased blood levels. Previous studies have suggested that environmental factors may influence blood Mn levels. As part of a community-based survey of potentially toxic environmental contaminants among pregnant women, the objective of this exploratory study was to examine the Mn status in pregnant women and their newborns with respect to sociodemographic and environmental variables. Pregnant women from Southwest Quebec were recruited in the first or second trimester through the public health prenatal program Mn was analyzed in mother's blood at entry into the study, in the second trimester (for those who entered during the first trimester), and at delivery, as well as in umbilical cord blood and in placental tissue. Sociodemographic data and information about pregnancy were obtained by two questionnaires; the first was administered at study entry and the second a few weeks following birth. Results showed that mothers' Mn blood levels increased significantly during pregnancy and cord blood Mn levels were significantly higher than those for mothers' blood. There was no relation to age. Smokers had significantly lower Mn blood levels compared to nonsmokers at the second trimester. Those who lived in urban and/or agricultural areas had significantly higher levels compared to those who lived in small villages. Those who reported pesticide spraying less than 1 km from their house likewise had significantly higher levels compared to the others. These findings suggest that lifestyle and environmental factors may interfere with the delicate balance and homeostatic mechanisms required to maintain Mn at optimal levels for physiological changes during pregnancy.

The placenta has been investigated as a possible indicator of environmental exposure. Levels of 8 trace elements (including Hg, Pb, and Cd) have been measured in placenta, maternal blood, and fetal blood. The trace element levels for the various tissues were correlated against one another. The elemental levels were also examined with respect to birth month, race, socio-economic status, etc. An attempt was made to determine relationships between elevated levels of particular elements and the increased occurrence of specific infant malformations.