Can you test for autism during pregnancy? What you need to know
October 30, 2024
While the prevalence of children diagnosed with autism spectrum disorder (ASD) has increased in recent decades, it’s not exactly clear why. Yes, health care providers are screening more children and have better tools for diagnosis. But what’s considered autism has also changed over time.
In our roles at UT Southwestern Medical Center, we see many pregnant patients anxious about the risk of autism for their baby. We are often asked whether it’s possible to test for autism during pregnancy.
The short answer is no, and here’s why:
- Children do not exhibit signs of autism in the womb – most diagnoses occur after 2 years of age, when a child doesn’t hit developmental milestones in the same way as their peers.
- There’s no single genetic test for autism – over 100 independent genes and over 100 chromosomal differences are thought to contribute to autism.
- There are no gene mutations that cause autism 100% of the time. While some mutations have been associated with autism, their presence means a diagnosis is more likely but not definite.
Autism spectrum disorder, as the name suggests, is a range of conditions and diagnosed through observed behaviors and characteristics rather than a specific medical test. Some people with autism will have severe behavioral and mental symptoms, while others will have more subtle symptoms. Autism affects how people think, communicate, and interact with others, and it can make them see and experience the world in unique ways. It's estimated that over five million adults in the U.S. (about 2.2% of the population) have autism.
Though genetic testing cannot tell whether your baby has autism or where he or she may be on the spectrum, a better understanding of autism can help you assess your child’s risk and what to look for.
Is autism genetic?
Genetic variations are thought to be a contributing factor in about 40%-80% of autism cases. Though current technology cannot test for all genetic factors thought to contribute to autism, we can test for certain mutations based on known parental symptoms or family history of genetic mutations associated with autism such as:
- Fragile X syndrome: This is the most common inherited cause for intellectual disability, and it can affect a person’s development, behavior, and ability to learn. About 33% of people with fragile X syndrome will develop symptoms similar to autism that affect social interactions and communication.
- Tuberous sclerosis: This condition is caused by genetic variants in the TSC1 and TSC2 genes, which normally regulate cell growth but can cause non-cancerous growths when mutated. About 26%-45% of people with tuberous sclerosis develop autism.
- PTEN mutations: Variants in this gene disrupt cell growth and hinder tumor suppression. About 25%-50% of children with PTEN mutations have autism symptoms.
- Down syndrome: This genetic condition is characterized by an extra chromosome, leading to developmental delays and physical differences. Up to 39% of people with Down syndrome can have autism as well.
- Chromosome abnormalities, such as 1p36 deletion: Deletions or duplications (missing or extra pieces) of chromosome material can also cause conditions that results in an increased risk for autism or other health problems.
What genetic tests are available?
It’s worth noting that even if a fetus tests positive for one of these genetic variations, it does not mean that the child will definitively develop autism.
There are several genetic testing options available during pregnancy. Carrier screening is a blood test that can be done on one or both parents to help to estimate the likelihood of a fetus having certain genetic conditions. Chorionic villus sampling (CVS) or amniocentesis are prenatal diagnostic tests that can give more definitive information about chromosomes or specific genetic conditions in the fetus. CVS is a test where a small sample of the placenta is taken to check for genetic abnormalities. Amniocentesis uses a bit of the amniotic fluid around the baby for the same reason.
Another option is noninvasive prenatal testing (NIPT), which can report the likelihood of common genetic variations in a fetus using a simple blood draw from the pregnant parent. NIPT can screen for Down syndrome, and depending on the type of NIPT, possibly other aneuploidies, but it can’t test for most specific genes.
Many cases of autism have no identifiable genetic link, meaning that there are multiple factors that could have led to the condition. These can include environmental influences, complications during pregnancy or birth, and even early life experiences. There may also be genetic causes that we don’t yet understand.
Which factors pose a higher risk for autism?
Other known risk factors for autism include:
- Having a previous child with autism. According to research, most children have a 3% chance of having autism, while children with siblings who have autism have about a 20.2% risk.
- Low birth weight. According to one study, infants with a low (less than 5.5 pounds) or very low (less than 3.5 pounds) birth weight have an increased risk of developing autism.
- Older parents. According to a survey covering over five million children in five countries, older parents, especially dads over 50 and moms over 40, had a higher risk of having a child with autism.
- Male sex: Boys are about four times more likely to be diagnosed with autism than girls.
What are some signs that my child has autism?
Autism is usually diagnosed when children do not reach certain developmental milestones, such as talking or walking. These usually become apparent around age 2, though some children won’t get diagnosed until later in life. Some symptoms to watch out for include:
- Social challenges: Difficulty with understanding and engaging in typical social interactions
- Repetitive behaviors and restricted interests: Engaging in repetitive actions and focusing intensely on specific topics or activities
- Communication difficulties: Difficulty speaking, understanding, or using language effectively
- Sensory sensitivities: Over- or under-reacting to sensory stimuli, such as lights, sounds, or textures
- Difficulty with changes in routine: Having problems with adapting to changes in daily routines and habits
These symptoms can tell your provider, with far more likelihood than a genetic test, whether you should pursue further diagnostic testing for autism.
What should I do if my child shows signs of autism?
The most important thing to do as a parent of a child who’s showing signs of autism is to observe and document behavior and consult your pediatrician as soon as possible. It’s likely that your pediatrician will need documentation of more than a few interactions to diagnose your child, so the more you can make note of, the better. Your pediatrician can:
- Arrange for your child to have a formal test, such a questionnaire, or give you instructions for an observation schedule.
- Connect you with specialists to help you and your child navigate autism.
- Help you find support groups and mental health resources for both you and your child.
- Help you support your child through their key developmental phases, including when they transition from high school to young adulthood.
If your child has been diagnosed with autism, remember that you did nothing to “give” them autism. The causes of autism aren’t clear, but they don’t boil down to any one decision you made during pregnancy or early childhood care.
Most people with autism will be able to live full lives, especially with support, understanding, and early intervention. For parents of children who have autism, the UT Southwestern and Children’s Health Center for Autism Care can help connect you and your child with therapists, support groups, and social workers. If your child has other conditions that are related to their autism, the center can also connect you with additional specialists for more holistic care.
Genetic testing during pregnancy won’t tell you whether your child will have autism, but you can test for certain conditions to help understand your risk. Regardless of your risk factors, your providers can help you prepare for birth and early development.
To talk with an expert about genetic testing, call 214-645-8300 or request an appointment online.
