Maternal–Fetal Exposure to Oncoelements and Their Oxidative and Epigenetic Impact on Pregnancy Outcomes

The proper course of pregnancy and fetal development depends, among other factors, on maintaining adequate levels of micronutrients in the maternal body. This integrative, concept-driven narrative review summarizes the current state of knowledge on the impact of selected elements, referred to as oncoelements, on placental function and obstetric outcomes. These include both potentially protective elements (selenium, zinc, copper) and toxic metals (cadmium, lead, arsenic), which, in excess may disrupt oxidative, hormonal, and epigenetic homeostasis. Rather than providing a quantitative synthesis, the article is structured around a four-level conceptual model integrating molecular mechanisms, placental protection, clinical outcomes, and umbilical cord blood as a biomarker of prenatal exposure. Mechanisms of toxicity include oxidative stress, mitochondrial dysfunction, DNA damage, and altered gene expression. Given the observational nature of most studies, clinical recommendations remain cautious. Micronutrient assessment may be useful in selected high-risk groups, but requires further validation. In environmentally burdened regions, screening for toxic metals may be considered. Future research should clarify dose-response relationships, define threshold concentrations, and explore molecular biomarkers of exposure. Umbilical cord blood offers a promising matrix for assessing fetal exposure, although interpretation is limited by methodological variability and the lack of reference values.