Autism and pregnancy: What science says about risk factors

By oliviacook // 2025-03-17

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Research suggests that prenatal factors – including genetic predispositions, environmental exposures, infections and maternal health conditions – may contribute to Autism spectrum disorders (ASD).
Conditions like obesity and gestational diabetes can increase ASD risk by triggering hormonal imbalances, inflammation and gut microbiome changes.
While some studies suggest a link between prenatal use of SSRIs and antibiotics and ASD, more research is needed to separate medication effects from the underlying health conditions they treat.
Exposure to diesel exhaust, heavy metals (such as lead and mercury), plastic chemicals (phthalates) and other toxins during pregnancy may disrupt brain development through hormonal interference, oxidative stress and inflammation.
Large-scale studies and personalized approaches to pregnancy care could help identify at-risk individuals, develop prevention strategies and improve early interventions for ASD.

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that affects how individuals communicate, interact and process the world around them. In recent years, the number of children diagnosed with ASD has increased significantly. While better awareness and improved diagnostic tools account for some of this rise, emerging research suggests that environmental factors – especially those during pregnancy – may also contribute. A new comprehensive review published in BMC Medicine in September 2024 explores the latest science on prenatal influences on ASD, shedding light on how genetics and environmental factors interact in early brain development. Scientists are now focusing on the prenatal period as a critical window for understanding autism risk. From maternal infections to air pollution, here’s what the latest research reveals.

The interplay of genetics and environment

ASD is not caused by a single factor but results from a complex interplay between genetics and environmental influences. Studies suggest that while genetics account for roughly 50 percent of ASD risk, environmental exposures during pregnancy can act as triggers or amplifiers. Some individuals may have a genetic predisposition to ASD, but whether they develop it can depend on prenatal conditions. Scientists believe that factors such as infections, maternal health, medications and environmental toxins can interact with genetic vulnerabilities, potentially disrupting early brain development.

Infections during pregnancy: A hidden risk?

Maternal infections during pregnancy—such as influenza, bacterial infections, or viral illnesses—have been associated with an increased risk of ASD. When a pregnant person’s immune system responds to infection, it releases inflammatory chemicals called cytokines, which can cross the placenta and impact fetal brain development. Studies in animals suggest that this maternal immune activation (MIA) may alter brain structure and function, potentially leading to ASD-related behaviors. (Related: FLU SHOT WARNING: Despite official recommendations, this vaccine endangers pregnant women and babies because it STILL contains MERCURY.) The link between inflammation and ASD risk is gaining traction, with researchers noting that immune system disruptions during pregnancy could have lasting effects on neurodevelopment. Interestingly, some studies suggest that controlling fever with antipyretic medications (like acetaminophen) might help mitigate this risk, though more research is needed.

Maternal health: The role of obesity and gestational diabetes

Emerging evidence suggests that maternal obesity and gestational diabetes mellitus (GDM) may influence ASD risk. Both conditions are associated with chronic inflammation, which can affect the developing fetal brain. Additionally, obesity and GDM can disrupt important hormones like insulin and leptin, which regulate fetal growth and metabolism. Some studies also indicate that these metabolic changes may alter the composition of the maternal gut microbiome, which plays a crucial role in immune system function and early brain development. Interestingly, research shows that the timing of GDM onset may matter. Women diagnosed with GDM earlier in pregnancy appear to have a higher likelihood of having a child with ASD compared to those diagnosed later. This suggests that prolonged exposure to abnormal glucose levels may play a role in neurodevelopmental disruptions.

Medications during pregnancy: A complex picture

The use of selective serotonin reuptake inhibitors (SSRIs), commonly prescribed antidepressants, has been studied for potential links to ASD. Serotonin is a key neurotransmitter involved in brain development, and SSRIs work by increasing its levels. Some studies have suggested that prenatal SSRI exposure could be associated with a slightly increased risk of ASD, but the evidence remains inconclusive. A major challenge in this research is distinguishing the effects of SSRIs from the effects of the underlying mental health conditions they are prescribed to treat. Since maternal depression itself has been linked to ASD risk, it’s unclear whether SSRIs contribute directly or whether untreated depression poses a greater risk. Most experts agree that treatment decisions should be made on a case-by-case basis, weighing the potential benefits and risks with a healthcare provider. Similarly, antibiotic use during pregnancy has been examined in relation to ASD. Some studies suggest that antibiotics may disrupt the maternal gut microbiome, leading to immune system changes that could influence fetal brain development. However, the type of antibiotic, timing of exposure, and underlying infection being treated all complicate the relationship, making it an area in need of further research.

Environmental toxins: A growing concern

Exposure to toxic substances such as plastic chemicals (phthalates), air pollutants, and heavy metals (lead, mercury) during pregnancy has been linked to an increased risk of ASD. These chemicals can interfere with hormonal balance, increase oxidative stress and trigger inflammatory responses that may disrupt brain development. Recent research has particularly focused on air pollution, with studies finding that prenatal exposure to diesel exhaust particles (DEPs) is associated with a higher likelihood of ASD. Animal models suggest that these pollutants may lead to immune system dysregulation, altering the normal development of microglial cells—key immune cells in the brain. However, much remains unknown about how different toxicants interact with genetic vulnerabilities in shaping ASD risk.

The gut-brain connection: A new frontier

One of the most intriguing emerging areas of research is the gut-brain connection and its role in ASD. The gut microbiome—the community of microbes living in the digestive tract—plays a major role in brain signaling, immune regulation and metabolism. Disruptions in the maternal microbiome during pregnancy may affect the developing fetus in ways that contribute to ASD. Animal studies have shown that altering the gut microbiome can lead to changes in social behavior, cognition and inflammation, all of which are relevant to ASD. While research in humans is still in its early stages, some scientists believe that microbiome-targeted therapies, such as probiotics or dietary interventions, could eventually be used as a preventive strategy.

Looking ahead: The future of ASD research

Understanding the prenatal risk factors for ASD is a critical step toward developing effective prevention strategies. Future research efforts are focusing on:

Longitudinal birth cohort studies to track how genetic and environmental factors influence ASD development over time.
Personalized medicine approaches, identifying genetic and environmental risk factors that could allow for targeted interventions.
Public health policies aimed at reducing prenatal exposure to risk factors like air pollution and toxic chemicals.
Microbiome research to explore the potential for gut-targeted therapies in reducing ASD risk.

ASD is a complex condition with no single cause or treatment, but research is uncovering new insights into how genetics and the prenatal environment interact to shape neurodevelopment. By identifying modifiable risk factors and understanding their underlying mechanisms, scientists hope to develop strategies that could lower ASD risk for future generations. Autism research is advancing rapidly, and while many questions remain, one thing is clear: the prenatal environment plays a crucial role in early brain development. For expecting parents, maintaining good prenatal health—by managing infections, maintaining a healthy diet, and minimizing exposure to harmful substances—may be beneficial. As research continues, healthcare providers and policymakers will be better equipped to provide guidance on reducing ASD risk and supporting families. Watch this video to learn more about the early signs and causes of autism. This video is from the Daily Videos channel on Brighteon.com.

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