Research indicates that genetics are involved in the vast majority of cases. Children born to older parents are at a higher risk for having autism. Parents who have a child with ASD have a 2 to 18 percent chance of having a second child who is also affected.
According to a study published in Molecular Autism, children born to mothers with autism have a 5.4% chance of also being diagnosed with the disorder, while children born to fathers with autism have only a 1.5% chance.
Multiplex families tended to have more children, and thus more chances to have another child with autism. The study combined males and females when analyzing the data, even though ASD rates are higher in males and symptom severity may vary between the sexes.
Having a family health history of ASD makes you more likely to have a child with ASD, or to have ASD yourself. If you have a child with ASD, you are more likely to have another child with ASD, especially if you have a daughter with ASD or more than one child with ASD.
The overall risk of having a child with autism is relatively low. The CDC says that the average risk is about 1.7%. But this risk goes up as the mother gets older. For women under 30, the chances of having a child with autism are about 1 in 500.
Among all families affected by autism, up to 19 percent have more than one child with the disorder, according to one large study. Multiplex families, especially those who have twins, have led to many of the breakthroughs in our understanding of autism.
Although the exact cause of autism is still unknown, there is evidence to suggest that genetics play a significant role. Since autism is less prevalent in females, autism was always thought to be passed down from the mother. However, research suggests that autism genes are usually inherited from the father.
When it comes to siblings, the research is clear: When one child is diagnosed with ASD, the next child to come along has about a 20% greater chance of developing ASD than a child with neurotypical older siblings. And when the first two children in a family receive that diagnosis, the chances go up to 32%.
There is not just one cause of ASD. There are many different factors that have been identified that may make a child more likely to have ASD, including environmental, biologic, and genetic factors.
They note that sibling relationships can be especially good for autistic children, and you can help build these relationships. All these parents say it's important to give all children love, time and attention, and they suggest ways you can do this.
In the largest study of its kind, researchers have shown that the risk of autism increases for firstborn children and children of older parents. The risk of a firstborn with an autism spectrum disorder triples after a mother turns 35 and a father reaches 40.
A 2022 study found that a routine second-trimester ultrasound could detect early signs of autism during pregnancy,18 including anomalies in the heart, head, and kidneys. These anomalies were found in 30% of fetuses who were later diagnosed with ASD, a three times higher rate than typical fetuses.
Rates of autism are highest in kids that are born to males over 50 years old. Genetic mutations in sperm rise as men become older, which might add to the risk. Although it's common for women to have children into their forties, they're also the most likely to produce an autistic child.
In the United States, prenatal genetic testing (PGT) for Autism Spectrum Disorders (ASD) is currently available via clinical genetic services. Such testing may inform parents about their unborn child's risk for ASD, prepare parents for the birth of an affected infant, and allow them to arrange for early interventions.
Children with an autistic parent or sibling have 9 times the usual odds of autism and 4.1 times the odds of having autism with intellectual disability.
It is estimated that 1 in 100 people in Australia have Autism. In 2018 there were 205,200 Australians with Autism, a 25.1% increase from the 164,000 in 2015 (Source: ABS SDAC 2018– Autism in Australia). This means that if you have Autism you are not alone.
Key Autism Statistics & Facts
In 2023, the CDC reported that around 1 in 36 children in the U.S. is diagnosed with autism. Autism prevalence has increased 178% since 2000. The country with the highest rate of diagnosed autism in the world is Qatar, and the country with the lowest rate is France.
A common question after an autism diagnosis is what is the cause of autism. We know that there's no one cause of autism. Research suggests that autism develops from a combination of genetic and nongenetic, or environmental, influences. These influences appear to increase the risk that a child will develop autism.
Genetic factors are estimated to contribute 40 to 80 percent of ASD risk. The risk from gene variants combined with environmental risk factors, such as parental age, birth complications, and others that have not been identified, determine an individual's risk of developing this complex condition.
Maternal diabetes or obesity are linked to increased likelihood of having a child with autism or other developmental disability. Fever during pregnancy was associated with increased risk of autism for children.
Because autism spectrum disorder varies in severity with each child, there is no hard and fast rule. It is not uncommon for children with ASD to begin developing speech in the same manner as typical children, as well as to regress in speech and language comprehension around two years old.
Autism is not an illness
It means your brain works in a different way from other people. It's something you're born with. Signs of autism might be noticed when you're very young, or not until you're older. If you're autistic, you're autistic your whole life.
Men and boys are more frequently diagnosed with autism than women and girls. It is debated whether this is due to a sex difference in rates of autism spectrum disorders (ASD) or whether females are underdiagnosed. The prevalence ratio is often cited as about 4 males for every 1 female diagnosed.
Autism Parents By Age
One study found that the chance of having ASD for children born to parents who are in their thirties is up to 10 percent higher than parents who are 25 to 29 years old. The same researchers found that the chance of developing ASD is 50 percent higher when the parents are in their 40s or 50s.