Autism Spectrum Disorder (ASD) is a developmental condition involving differences in communication, social interaction, and sensory experiences. There is no single cause of autism; its development involves a complex interaction between genetics and various environmental influences. A risk factor is a condition or exposure that statistically increases the likelihood of an outcome, not a direct cause that definitively produces an effect.
Parental Genetics and Advanced Age
Genetic factors contribute significantly to the likelihood of developing autism, which helps explain why ASD can run in families. The presence of ASD in an older sibling, for example, is a known risk factor for subsequent children. While the specific genes are numerous and their interactions complex, this genetic foundation sets a baseline for risk before pregnancy.
Advanced parental age is a well-documented risk factor. The chances of having a child with autism increase for both older mothers and fathers, with research indicating a heightened risk for mothers over 40 and fathers over 50. This is thought to be related to the increased chance of spontaneous genetic mutations in the reproductive cells of older parents.
Maternal Health Conditions
Maternal Immune Activation (MIA), a heightened inflammatory state in the mother, is one area of focus. MIA can be triggered by severe infections like influenza or by chronic inflammatory conditions such as autoimmune diseases. The resulting inflammatory response can produce molecules that cross the placenta and influence the developing fetal brain. Studies have linked hospitalizations for severe infections during pregnancy to a higher likelihood of autism.
Metabolic conditions in the mother are another risk factor. Conditions like obesity, type 2 diabetes, and gestational diabetes can create an inflammatory environment. Research has found that a diagnosis of gestational diabetes by the 26th week of pregnancy was associated with a greater likelihood of autism. Exposure to elevated blood sugar levels from these conditions may affect the fetus’s neurological development.
Prenatal Environmental and Nutritional Factors
Exposure to certain substances during pregnancy can influence developmental outcomes. For instance, taking the anti-seizure medication valproic acid during pregnancy has been linked to a higher chance of a child developing autism. Other environmental exposures, such as high levels of air pollution and certain pesticides, have also been correlated with increased risk, though research is ongoing.
Nutritional status during pregnancy is another element. A deficiency in iron, which is important for neurological development, has been associated with a higher risk of autism.
Conversely, sufficient intake of certain nutrients may lower the risk. Multiple studies show that taking a folic acid supplement in early pregnancy is associated with a significantly lower risk of a child developing autism. For this reason, healthcare providers recommend folic acid supplements for anyone who could become pregnant.
Complications During Birth
The perinatal period, the time just before, during, and after birth, has its own risk factors. Premature birth, defined as delivery before 37 weeks, is a recognized risk factor. A low birth weight for the baby’s gestational age has also been linked to a higher likelihood of an autism diagnosis.
Events during labor and delivery can also contribute to risk. Situations leading to fetal distress or hypoxia, a lack of adequate oxygen to the brain, have been identified as potential factors.