As an ABA therapist, I often meet families who wonder what might have caused their child’s autism—and whether pregnancy had anything to do with it. It’s a question that’s filled with worry, curiosity, and sometimes guilt. So let’s clear the air.

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition influenced by both genetics and environmental factors. While our genes may lay the groundwork, certain maternal conditions, exposures, or health decisions during pregnancy can potentially shape how a child’s brain develops. 

Here’s what we know—and what we don’t—when it comes to pregnancy and autism risk.

The Interplay Between Genetics and the Environment

Genetics Set the Stage, But They’re Not the Whole Story

In my experience, genetic predisposition is a strong factor when it comes to autism. We often see patterns in families—siblings, cousins, even parents with traits that fall somewhere on the spectrum. Twin studies have shown that identical twins are much more likely to both be autistic than fraternal twins, which really speaks to that genetic influence.

But genes alone don’t dictate outcomes. Dozens—sometimes hundreds—of genetic variants may be involved, and they interact in complex ways that affect how the brain develops. Some of these are tied to known syndromes like Fragile X or Rett syndrome. Others are still being uncovered.

Interestingly, the way genes are expressed might even differ between males and females, which could help explain why boys are diagnosed with autism more frequently.

How the Environment Can "Switch On" or "Off" Our Genes

We now understand that genes don’t operate in a vacuum—they respond to the environment, especially during critical periods of fetal development. This is where things get really interesting.

There’s a concept called epigenetics, which refers to how environmental factors can influence gene expression. For example, if a mother experiences high levels of stress or contracts certain infections during pregnancy, the resulting immune responses might affect how genes are expressed in the baby’s developing brain.

Pollutants, poor nutrition, or exposure to toxins can also increase something called oxidative stress, making it harder for the fetal brain to develop smoothly—especially if there’s already a genetic vulnerability in play.

Key Environmental Risk Factors During Pregnancy

The Impact of Air Pollution and Toxic Chemicals

Air quality matters more than most people realize. Research suggests that prenatal exposure to air pollution—like diesel exhaust—can increase inflammation in the developing brain, which may raise the risk of autism.

Other toxins, including heavy metals like mercury or lead, are also concerning. They can interfere with normal brain cell functioning, and when combined with other maternal risk factors, the risks can multiply. 

In my line of work, I often recommend minimizing exposure to these pollutants with practical steps—like using air filters or being mindful of traffic-heavy areas during pregnancy.

Pesticides and Industrial Chemicals

Another area of concern is exposure to pesticides and industrial chemicals, especially those used in agriculture and manufacturing. Some pesticides have been shown to trigger inflammatory responses in the brain, which is one of the mechanisms thought to be involved in autism.

Other chemicals, like phthalates found in plastics, can mimic hormones and interfere with brain development. While the research is still ongoing, I always advise pregnant clients to lean toward organic produce and reduce use of products with known chemical hazards.

Household and Beauty Products: A Hidden Source of Exposure

Many of us don’t think twice about our cleaning sprays or beauty products—but some of them contain chemicals linked to oxidative stress, which, again, can affect how the fetal brain develops.

Common culprits include phthalates and parabens found in fragrances, shampoos, and even makeup. I usually suggest switching to more natural, non-toxic options during pregnancy. It’s a small but powerful step in creating a safer environment for baby.

Maternal Health and Lifestyle Habits

Nutrition: Building a Brain from the Inside Out

Maternal nutrition is crucial—it's quite literally the fuel for your baby’s developing brain. Nutrients like folic acid play a key role in forming neural pathways, and a deficiency can disrupt brain growth in significant ways.

I always encourage expectant mothers to prioritize a well-rounded diet full of leafy greens, omega-3s, and prenatal vitamins. Research shows that folic acid, when taken before and during early pregnancy, may lower the risk of ASD.

Stress and Mental Health: More Than Just a Feeling

Stress is a big one. High levels of maternal stress can lead to immune system changes that affect fetal brain development. Anxiety and depression during pregnancy aren’t just hard on the mom—they can actually alter how a baby’s brain wires itself.

In my experience, managing stress through therapy, support systems, or even simple mindfulness techniques can make a meaningful difference—not just for the mother’s well-being, but for the child’s development too.

Lifestyle Choices That Affect Risk

The Risks of Recreational Drugs and Alcohol

Substance use during pregnancy can have long-lasting impacts on brain development. Alcohol, for instance, is linked to fetal alcohol spectrum disorders, which can look very similar to autism in terms of social and behavioral challenges.

Recreational drugs can also interfere with neural connections and developmental milestones. I always encourage families to view pregnancy as a time to reduce or eliminate exposure to any non-essential substances—for the sake of both mother and baby.

Medical Conditions That Can Raise Autism Risk

How Maternal Diabetes Plays a Role

Gestational diabetes doesn’t just impact the mother—it can affect the baby’s brain development, too. Elevated blood sugar levels can trigger inflammatory responses that may influence the expression of genes related to ASD.

It’s also worth noting that obesity, often connected to diabetes, introduces additional risks through oxidative stress and hormonal imbalances.

Thyroid Disorders and Neurodevelopment

Thyroid hormones are key regulators of fetal brain development. Both hypothyroidism and hyperthyroidism during pregnancy have been linked to delays and neurodevelopmental issues, including autism.

That’s why I always recommend regular screening and proactive management of thyroid conditions during pregnancy.

The Connection Between Autoimmune Conditions and Autism

Autoimmune conditions like lupus or rheumatoid arthritis can lead to maternal immune activation, which may alter fetal brain development. In some cases, this immune activity is believed to affect the baby’s gene expression in ways linked to ASD.

For women with autoimmune conditions, working closely with a healthcare provider during pregnancy is essential to reduce risks and ensure both maternal and fetal health are protected.

Medications and Their Effects on Fetal Development

Antidepressants: A Delicate Balance

This one comes up a lot. While mental health support during pregnancy is so important, there’s emerging research linking certain antidepressants—especially SSRIs—to a slightly increased risk of autism.

That doesn’t mean women should stop taking their medication. Instead, I advise open, honest conversations with doctors about the risks and benefits so everyone can make the best choice for their unique situation.

Anti-Epileptic Medications and Development

Anti-epileptic drugs are another class of medications linked to developmental risks. These medications are essential for some, but prenatal exposure has been associated with higher ASD risk in several studies.

In situations like this, coordinated care between neurologists, OB-GYNs, and mental health professionals is key to balancing the mother’s needs with the baby’s development.

What About Over-the-Counter Medications?

Many people assume over-the-counter drugs are safe—but some can still affect fetal development. Certain ingredients may trigger oxidative stress or immune responses, which we know can play a role in neurodevelopment.

So even with seemingly “mild” medications, I always recommend consulting a doctor during pregnancy. Better safe than sorry when it comes to brain development.

As someone who works closely with children on the spectrum and their families, I know how easy it is to fall into cycles of worry or self-blame when you’re trying to understand why. But the truth is, autism has no single cause. It’s a complex interplay of factors—some we can control, and many we can’t.

What we can do is focus on creating a healthy pregnancy environment: eat well, reduce exposure to harmful substances, manage stress, and work with healthcare providers to monitor existing health conditions. Every small step adds up.

And if your child does receive an autism diagnosis one day? Remember this: you’re not alone. Early intervention, like ABA therapy, can make a meaningful difference—and you have support every step of the way.

Reach out to Blossom ABA Therapy today and discover how early, personalized support can make all the difference.

FAQs

Can stress during pregnancy cause autism?

While stress alone doesn’t cause autism, chronic stress may influence fetal brain development, especially when combined with other risk factors.

Is autism caused by something the mother does during pregnancy?

No single action causes autism. It's a complex mix of genetics and environmental influences—not the result of one choice or behavior.

Can taking medication during pregnancy increase autism risk?

Some medications, like certain antidepressants or anti-epileptics, have been linked to a slightly higher risk. Always consult your doctor for safe options.

Sources:

• https://pmc.ncbi.nlm.nih.gov/articles/PMC6421839/

• https://pmc.ncbi.nlm.nih.gov/articles/PMC8902545/

• https://www.thetransmitter.org/spectrum/link-parental-age-autism-explained/

• https://www.cdc.gov/autism/about/index.html

• https://nyulangone.org/news/no-evidence-maternal-sickness-during-pregnancy-causes-autism

• https://www.science.org/content/article/giant-study-questions-link-between-autism-and-maternal-health

• https://publichealth.jhu.edu/2016/too-much-folate-in-pregnant-women-increases-risk-for-autism-study-suggests