Maternal-fetal exposure to medications and environmental toxins represents a major issue in public health and developmental biology. Numerous toxic substances can cross the placental barrier via passive diffusion or active transport, thereby exposing the fetus to compounds that its still-immature organism struggles to eliminate.
The placenta, a vital interface between mother and fetus, ensures the supply of oxygen and nutrients essential for fetal development. It also plays a partial role in the elimination of xenobiotics. These foreign substances must be metabolized before they can be excreted—a process that primarily takes place in the liver but can also involve the kidneys, skin, and lungs. This metabolism occurs in two phases: Phase I, mainly carried out by the cytochrome P450 enzyme system, produces often reactive metabolites; Phase II involves conjugation reactions that make these metabolites water-soluble for urinary excretion.
In the fetus, hepatic immaturity limits the biotransformation of xenobiotics, making elimination largely dependent on maternal liver and kidney function. The placenta, which also expresses certain CYP450 enzymes, contributes to this detoxification process, particularly regarding pesticides during gestation. However, this protection is not absolute: transplacental passage remains possible, as evidenced by the detection of toxic residues in newborn urine, meconium, or cord blood.
Fetal vulnerability is further increased by the heightened permeability of the developing blood-brain barrier. The agents involved include certain medications (e.g., antiepileptics), illicit drugs (cocaine, heroin), environmental toxins (heavy metals, endocrine disruptors, pesticides), as well as alcohol and tobacco. Such exposures can lead to congenital malformations, neurodevelopmental disorders, intrauterine growth restriction, prematurity, or even fetal death.
The effects may extend well beyond birth. Prenatal exposures have been linked to the later development of chronic diseases in adulthood, such as obesity, diabetes, and cognitive disorders.
Prevention relies on proactive patient education, strict regulation of teratogenic and polluting substances, and public health policies aimed at minimizing risk exposures during pregnancy.

Prenatal exposures to environmental factors have garnered significant attention due to their potential impact on fetal development and long-term health outcomes. This presentation reviews current evidence from human studies exploring prenatal exposures to various environmental stressors, including chemicals, pollutants, and lifestyle factors. Emphasizing recent trends and advancements in research methodologies, the session will highlight key findings linking prenatal exposures to developmental outcomes, neurobehavioral effects, and diseases. Attendees will gain a comprehensive understanding of the current state of prenatal exposure research, its implications for maternal and child health, and future directions for advancing knowledge.

Risk assessment for maternal and child health in relation to chemical exposures has evolved slowly in recent years. Traditional approaches have largely focused on individual chemicals and dose-response relationships, neglecting the complexity and ubiquity of real-world exposures. However, growing evidence on the developmental impacts of multiple, low-dose exposures is prompting a gradual shift toward more integrative frameworks.
Modern methodologies increasingly incorporate cumulative exposure models and consider emerging contaminants, as well as previously overlooked windows of susceptibility such as the preconception period and paternal exposures. These approaches recognise that chemical impacts can occur through diverse pathways and across life stages. Technological advances, including real-time monitoring and machine learning, offer new possibilities for improving exposure detection and data integration.
Nonetheless, significant challenges remain, particularly in assessing risks from chemical mixtures and substances with limited toxicological data. In this context, toxicology laboratories are pivotal to progress. By refining specimen analysis techniques and expanding biomarker panels, they enhance the detection of emerging contaminants and support the development of more robust cumulative risk models.
To further strengthen these frameworks, toxicology laboratories should play a greater role in integrating biomonitoring data with computational models and machine learning platforms. Additionally, clinical studies evaluating antenatal interventions to mitigate chemical exposures could provide critical insights into the long-term health consequences of early-life chemical burdens. Such efforts are essential for advancing public health strategies aimed at protecting vulnerable populations from complex chemical exposures.