Biological and infectious factors
Several prenatal biological factors are associated with later neurodevelopmental disorders. Maternal infection and immune activation during pregnancy are linked to increased risks of autism spectrum disorder and other developmental conditions. Irva Hertz-Picciotto at University of California Davis has led epidemiological studies showing that timing and severity of maternal infection influence outcomes, suggesting that maternal immune responses can alter fetal neurodevelopment. This is not deterministic; many infections do not produce lasting harm, and effects interact with genetics and other exposures.
Substance exposure and nutrition
Exposure to alcohol, tobacco, and certain medications in utero raises risk for cognitive, behavioral, and motor deficits. The National Institute on Alcohol Abuse and Alcoholism emphasizes that prenatal alcohol exposure causes fetal alcohol spectrum disorders, which carry lifelong neurodevelopmental consequences. Fiona K. Thapar at Cardiff University has emphasized caution in interpreting associations between maternal smoking and attention-deficit/hyperactivity disorder because genetic and environmental confounding can shape findings; nonetheless, smoking remains a preventable risk factor tied to poorer neurodevelopmental outcomes. Nutritional factors are also critical: inadequate folate before and during early pregnancy increases risk of neural tube defects and may influence broader neurodevelopment, a relationship that underlies public health folic acid recommendations from the Centers for Disease Control and Prevention.
Metabolic, environmental, and social contributors
Maternal obesity, gestational diabetes, and exposure to environmental pollutants such as air pollution and certain heavy metals are associated with elevated risks of autism and other neurodevelopmental disorders in cohort studies. These exposures often cluster with socioeconomic and territorial disparities: communities with limited access to healthy food, prenatal care, and clean environments face compounded risk. Mechanisms are complex and may involve inflammation, placental function, and epigenetic changes rather than a single causal pathway.
Pregnancy care that reduces preventable risks—vaccination where appropriate, management of chronic conditions, nutritional supplementation, avoidance of alcohol and tobacco, and reduction of environmental exposures—can lower population risk. Evidence-based interpretation requires attention to study design and confounding; leading researchers and public health agencies stress that prenatal factors interact with inherited susceptibility and postnatal environments to determine outcomes, producing a spectrum of possible consequences rather than uniform effects.