Most researchers agree that people are born with autism spectrum disorder (ASD). While research does shows some possible risk factors for the condition, most cases of ASD have no known cause.

According to recent estimates, about 1 in 100 children are diagnosed with ASD globally, continuing an ongoing diagnosis increase trend.

However, this increase is more likely due to greater awareness, a better understanding of the condition, and better diagnostic tools.

According to the Centers for Disease Control and Prevention (CDC), most scientists agree that genetics affect your chances of developing ASD. But in-utero exposure to some environmental factors may also play a part.

The term “risk factors”

This article refers to “risk factors” in relation to available research about ASD. However, it’s important to note that this term may have a negative connotation as many autistic people do not view being autistic as a disability, as a negative, or as something that needs to be cured.

Learn more about ASD.

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ASD is likely related to both nature and nurture – in other words: Genetics and environment. It does not discriminate based on geographic location, culture, ethnicity, or socioeconomic status. However, it appears to be more common in males than females.

Some studies have shown that the developing brains of autistic people are wired differently than those who are neurotypical. Other studies show anatomical differences, such as size, in the brains of autistic individuals.

Are sex and gender the same thing?

People often use the terms sex and gender interchangeably, but they have different meanings:

  • “Sex” refers to the physical characteristics that differentiate male, female, and intersex bodies.
  • “Gender” refers to a person’s identity and how they feel inside. Examples include man, woman, nonbinary, agender, bigender, genderfluid, pangender, and trans. A person’s gender identity may differ from the sex they were assigned at birth.
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Genetic factors

Research suggests that around 102 different genes may be implicated in the chance of being born autistic.

If you have an autistic brother, sister, twin, or parent, you’re more likely to be autistic as well. For example, if one identical twin receives a diagnosis of ASD, the chance that the other twin is also autistic is 60-90%.

Examples of genetic conditions that may increase your chance of being born autistic:

The CDC also reports that ASD rates are much higher among children with tuberous sclerosis than in those who don’t have the disease. Prader-Willi syndrome has also been linked to ASD.

Environmental factors

Studies show that parental exposure to heavy metals and other environmental toxins during pregnancy may raise the chance of being born autistic.

Some prescription drugs that may be used in pregnancy have also been linked to ASD. These include valproic acid and certain selective serotonin reuptake inhibitors (SSRIs).

That said, the research on whether SSRIs contribute to autism during pregnancy is inconclusive. Research has also found a rise in ASD rates among babies born to parents with untreated mental health conditions. So studies have not been able to determine whether ASD is associated the medications, the underlying condition, or with other undetermined factors.

Some research has also shown an association between certain viral infections or metabolic imbalances and the chance of being born autistic. Children born to older parents are also at a greater chance, according to the CDC. However, not all studies have found similar results, so more research is needed in this area.

Other prenatal factors may also affect a child’s chance. These may include:

A pregnant person’s diet is also an essential factor, as it may provide protective effects for people exposed to certain environmental pollutants. For example, taking prenatal vitamins, especially those containing vitamin D and folic acid, have proven to be very important to the developing fetus.

Sufficient research has shown that ASD develops before birth from a combination of genetic and environmental factors. But some misconceptions about ASD still remain.

Common symptoms in children, such as challenges with social communication or restrictive behaviors, can begin to be noticeable in early childhood. But the belief that something can cause ASD after birth may be related to the fact that not everyone is diagnosed during childhood.

Since ASD is a spectrum of conditions with wide-ranging symptoms, some autistic people are not identified as autistic until they are adults, especially autistic females.

Many autistic adults may also be masking their symptoms. In addition, research shows that children from historically marginalized groups are more likely to be undiagnosed or diagnosed later than people who are white.

Things that some may believe are risk factors but are not include:

Bad parenting

Contrary to popular belief, your style of parenting cannot cause your child to become autistic.

That said, it can be challenging to understand and support your autistic child. If you experience anxiety or frustration, this could affect your interactions with your child and contribute to the intensity of their symptoms.

For this reason, it’s a good idea to prioritize your self-care so that you can parent with sensitivity and support your child as they grow.

Read more about available resources for parents of autistic children and adolescents.


The idea that vaccines cause ASD is one of the most widespread myths related to the condition.

No scientific evidence supports that vaccinations cause ASD, including those containing thimerosal. Independent groups of medical experts in the United States have extensively,y reviewed this question for almost 20 years.

Some people have suggested that the MMR vaccine, specifically, may cause ASD. However, many scientific articles have refuted the connection between the MMR vaccine and ASD.

Vaccines are safe, effective, and critical to preventing children from getting potentially life threatening diseases.


As previously stated, people are born autistic. Therefore, your diet cannot cause you to be autistic.

While a pregnant person’s diet may play a role in the chance of a baby being born autistic, a child cannot become autistic after birth, no matter what they eat.

While it is more common for autistic children to display particular behaviors such as extreme food selectivity and refusal of foods, this is a feature of ASD rather that a risk factor. Food selectivity in autistic people is thought to be caused by an over-sensitivity to the taste or texture of certain foods.

Ultimately, nutrition and diet are essential for people with ASD to remain healthy and to prevent co-existing medical conditions. But no specific foods can cause ASD if you haven’t already been born autistic.

What is the leading cause of autism?

No single cause or risk factor for ASD has been determined. Researchers agree that you are born autistic, but the reasons for this are complex and not fully understood.

Is screen time associated with ASD?

It has been theorized that screen time, such as entertainment on television, computer, tablet, phones, or video games, may negatively impact children’s cognitive, social, emotional, and physiological development. However, the research does not directly establish screen time as a cause of ASD.

What foods can cause autism during pregnancy?

No particular food or food group is associated with ASD. One 2022 meta-analysis of 36 studies suggests that taking prenatal multivitamins and consuming enough folic acid and vitamin D are associated with a lower chance of having an autistic child.

What increases the risk of autism in pregnancy?

In addition to the factors already discussed in this article, research has found that problems with hormones, diabetes, and exposure to chemicals during pregnancy might be related to ASD in children.

How can I reduce my risk of autism during pregnancy?

Since the causes of autism are complex, it is difficult to account for every possible risk factor. Certainly, leading a healthy lifestyle during pregnancy can help protect the health of the baby. That said, current medical thinking is that ASD is not a condition that needs to be prevented or cured. For autistic children or adults who need it, support is available.

Learn more about resources for living with ASD.

ASD is a spectrum of neurological conditions. Autistic people are born autistic and remain autistic for their entire lives. ASD is not a disease, and it has no cure. Some genetic and environmental risk factors may be involved in developing ASD before birth.

While there has been an increase in the number of people diagnosed with ASD over the past few decades, this is not because ASD is becoming more frequent but because our understanding of ASD has developed over time, as has our ability to diagnose it. Because of this, there are more options for support than ever.