What Causes Autism in Children: 5 External Risk Factors

Reviewed by:

March 7, 2022

There is not one specific known cause of autism in children. Research shows that autism can form from a variety of genetic and environmental factors.

Autism's genetic risk factors

Autism tends to run within families and can be caused by several genes. Even if a parent does not have autism, certain genes that increase the risk of autism may be passed down to their children. These genes can also occur organically in an early embryo or in the fertilization process.

Autism's external risk factors

Both genetics and environment can influence whether a person gets autism, according to the National Institute of Neurological Disorders and Stroke Trusted Source.


Research shows one of the largest risk factors for autism is parental age. Parents who have children when they are older than 34 have seen a greater risk of autism in their children.

Maternal health 

A few physical symptoms associated with child autism include metabolic syndrome, bleeding, and maternal infection in pregnancy. There is a large increased risk of autism linked to maternal hemorrhage during pregnancy. There is also a correlation between a mother’s weakened immune system and autism in children. 

Familial socioeconomic status

Families that suffer financial difficulties and stress may also experience an increased risk of autism within their children. Specifically, the increased risk comes from stress from pregnant moms. 

Metals, pesticides, and other contaminants 

Heavy metals like mercury, lead, or arsenic, and changed levels of critical elements like zinc or manganese, pesticides, and other pollutants, are all causes for concern throughout pregnancy and early life. Baby teeth were utilized in the research of twins to measure and analyze amounts of lead, zinc, and magnesium in children with autism and their neurotypical twin. During specific developmental periods tested, children with autism exhibited lower amounts of manganese and zinc but had greater lead levels. Manganese and zinc are essential for development, growth, and functioning, while lead is hazardous to all of these.

Vaccines do not cause autism

Extensive research over the past two decades have shown that there is no link between vaccines and autism.

How does autism affect a child's social skills?

Interacting with people is difficult for a child with autism. Autism can cause information miscommunication, interpersonal misinterpretation, repetitive behaviors, and an inability to perform well in school, employment, and other aspects of life. 

Around 40% of children with autism do not speak at all, while approximately 25% and 30% have some language abilities during infancy, but lose those abilities later. Several children with autism do not begin to speak until later in life. 

Autism symptoms in small children include:

  • Nonresponsiveness to their name
  • Avoiding direct eye contact
  • Not returning smiles from others
  • Becoming enraged if they don't like a specific flavor, smell, or sound
  • Repeatedly waving their hands, twitching their fingers, or twisting their bodies
  • Flat affect in comparison to other children
  • Repeating the same words, phrases, or sentences over and over

Children with autism also behave in atypical ways or have strange interests, which include:

  • Hand flapping, swaying, bouncing, or whirling
  • Pacing (constant movement) and "hyper" behavior
  • Fixation on particular activities or items
  • Excessive impulsivity (acting without thinking)
  • Self-injurious behavior 
  • Aggression toward others
  • Limited attention span
  • Routines or rituals that have not been taught or are not functional
  • Extremely high responsiveness to contact, light, and noise
  • Skill deficits in pretend play or imitating other people's actions
  • Obsessive eating habits
  • Clumsiness, lack of coordination


Although there is no cure for autism, there are treatments available. Early detection and intervention are the most beneficial since they can aid behavior, abilities, and literacy skill development. Though children with autism do not generally outgrow their symptoms, they can function successfully. Parents can improve your chances of raising a healthy child by making the following lifestyle changes:

  • Live a healthy lifestyle. Maintain a healthy lifestyle by getting regular checkups, eating well-balanced meals, and exercising. Ensure you get appropriate prenatal care and take all of the advised vitamins and nutrients.
  • Don't consume excessive medication while you're pregnant. Before taking any medicine, consult your doctor. This is particularly true of several anti-seizure medications.
  • Avoid consuming alcoholic beverages. During pregnancy, say no to any alcoholic beverages.

Seek medical help if you already have any health problems. If anyone has been diagnosed with celiac or PKU, stick to your doctor's recommendations for managing your symptoms.


Autism is a complex neurodevelopmental condition that can be caused by various environmental and genetic factors. Over the previous few decades, the rates of autism have risen. While there are no blood exams to identify autism, there are comprehensive diagnoses. 

If you have any questions about autism diagnosis or therapy, contact us at Songbird therapy. Songbird is a technology-enabled provider setting a higher standard for children’s autism care. With a deeply passionate team and innovative technology, we’re building a world where every child can access world-class care at home, uniquely tailored to them.