Autism spectrum disorders (ASDs) is a group of conditions that affect how a child functions in several areas, including speech, social skills and behavior. Symptoms of these disorders vary greatly and range from mild to severe.
There are three main types of ASDs (1):
- Autistic disorder (also called classic autism): Affected individuals often have severe speech, social and behavioral problems. Sometimes individuals also have intellectual disability.
- Asperger syndrome: Affected individuals have milder social and behavioral problems than individuals with autistic disorder. They usually have normal speech and intellectual abilities.
- Pervasive developmental disorder not otherwise specified (also called atypical autism): Affected individuals have some symptoms, often including speech and social problems, but not enough to be diagnosed with classic autism.
The American Academy of Pediatrics (AAP) recommends that all children be screened for ASDs at their regular medical checkups at 18 months and 24 months (2). Early diagnosis and treatment can greatly improve the outlook for children with ASDs.
ASDs may affect about 1 in 110 to 1 in 150 children in the United States (3, 4). This means there may be more than 650,000 children in this country who have some symptoms of autism (4).
More children than ever are being diagnosed with ASDs. The rates of children diagnosed with ASDs have risen dramatically since the 1980s; between 2002 and 2006 they increased 57 percent, from 6.0 to 9.4 cases per 1,000 (3). Much of this increase may be due to improved awareness and changes in how ASDs are diagnosed.
Each child with an ASD is unique. Common characteristics and behaviors include a child who (1, 5):
- Does not speak (about 40 percent of children with autistic disorder do not speak at all)
- Repeats words
- Performs repetitive movements, such as hand-flapping
- Doesn’t play “pretend” games
- Is overly active
- Has frequent temper tantrums
- Avoids eye contact
- Has difficulty starting and maintaining conversation and making friends
- Does not respond to being called by name
- Insists on keeping the same routine
- Repeats actions again and again
- Focuses on a single subject or activity
- Wants to be alone
- Is overly sensitive to the way things feel, sound, taste or smell
- Dislikes being held or cuddled
- Has sleep disturbances
- Lacks fear in risky situations
- Has some degree of intellectual disability or learning problems
- Is aggressive
- Hurts himself
- Loses skills (for example, stops saying words he used to say)
A child with an ASD usually does not look different from other children. He may appear to develop normally for the first year or so of life. But during the second year, some children with an ASD begin to fall behind in social skills, fail to develop speech, or even lose skills that they had previously acquired. An ASD is often diagnosed around age 3; however, subtle signs of the disorder may appear before 18 months (2). These signs may include (2):
- Not turning when the parent says the baby’s name
- A lack of back-and-forth babbling with parents starting around 6 months of age
- Late smiling
- Not looking when a parent points and says, “Look at…”
Toddlers with these signs do not necessarily have an ASD, as each child develops at a different rate. However, parents should discuss these possible signs and other developmental concerns with their baby’s health care provider.
Speech delays can be early signs of ASDs. AAP recommends an immediate evaluation for ASDs if the child (2):
- Does not babble, point or use other gestures by 12 months
- Does not say any single words by 16 months
- Does not say any 2-word phrases by 24 months
- Loses language or social skills at any age
There is no specific medical test to diagnose ASDs. Health care providers generally diagnose ASDs by observing a child’s behavior. They also use screening tests that measure a number of characteristics and behaviors associated with ASDs. If a screening test suggests a possible problem, the provider may do additional tests or recommend evaluation by a specialist.
ASDs occur in all racial, social and educational groups. Boys are about 4 times more likely than girls to be affected (1). Siblings of an affected child may be at increased risk of ASDs, though the risk appears fairly low at 2 to 8 percent (1, 2).
Recent studies suggest that premature babies may be at increased risk of symptoms associated with ASDs (6, 7). A premature baby is a baby born before 37 weeks of pregnancy. Some of the increased risk is because of the higher rates of problems associated with premature birth (7, 8, 9). These problems include:
- Pregnancy complications, such as preeclampsia, a pregnancy-related form of high blood pressure
- Newborn health problems, such as brain bleeds
- Lasting disabilities, such as cerebral palsy, intellectual disabilities, and vision and hearing impairments
We don’t really understand the causes of ASDs. But scientists do know that autism is not caused by poor parenting or other social factors. It is a biological disorder that appears to be associated with subtle abnormalities in specific structures or functions in the brain.
Genetic and environmental factors appear to play a role in the disorder. Scientists believe that many genes on different chromosomes may be a cause. A research team recently identified a small gene region on chromosome 5 that may be associated with 15 percent of ASD cases (10). Another study found that abnormalities in a small region of chromosome 16 were about 100 times more common in children with ASDs than in unaffected children (11). Certain infections that occur before birth (such as rubella and cytomegalovirus) and older maternal age also have been associated with ASDs (2, 12).
About 10 percent of children with ASDs have other genetic diseases, including (1, 2):
- Fragile X syndrome (intellectual disabilities and behavioral problems)
- Tuberous sclerosis (non-cancerous tumors that affect the brain and other organs)
- Down syndrome and other chromosomal birth defects
Childhood vaccines, including the measles/mumps/rubella (MMR) vaccine, do not cause ASDs. Many studies have shown no link between the MMR vaccine and ASDs. In fact, the controversial 1998 study that set off concerns about a possible link between the MMR vaccine and ASDs was recently retracted by the medical journal Lancet that originally published it (13).
Some parents of children with autism suspected that the MMR vaccine, given around 12 to 15 months of age, contributed to ASDs because their children began to display symptoms of ASDs around the time they were vaccinated. Most likely, this is the age when symptoms of the disorder commonly begin, even if a child is not vaccinated.
Another reason that childhood vaccines were suspected of playing a role in ASDs is that, until recently, they contained a small amount of a preservative called thimerosal. Thimerosal contains mercury. While higher doses of certain forms of mercury may affect brain development, studies suggest that thimerosal does not. Since 2002, most routine childhood vaccines have not contained thimerosal. Some flu shots contain thimerosal, but parents can request flu shots that are thimerosal-free.
In 2004, an Institute of Medicine panel concluded, after reviewing many studies, that neither the MMR vaccine nor vaccines that contain thimerosal are associated with autism (14). A 2008 study found that the rate of ASDs in California continued to increase after thimerosal was removed from childhood vaccines, also suggesting a lack of association between thimerosal and ASDs (15).
Children often show great improvement with intensive behavioral treatment beginning during the preschool years. A recent study of children diagnosed with ASDs between the ages of 18 and 30 months found significant improvements in IQ (nearly 18 points), language skills and behavior after 2 years of participation in a behavioral intervention program designed for toddlers (16). The AAP recommends that infants and toddlers suspected of having an ASD be referred immediately to an early intervention program (2).
There is no cure for ASDs. However, some children benefit from medications that help improve their behavioral symptoms so that they are better able to learn. Some commonly used medications include:
- Anti-depressants and anti-anxiety drugs.
- Anti-psychotics: A new anti-psychotic drug called risperidone (Risperdal) is the only drug that is approved by the Food and Drug Administration (FDA) specifically for autistic behaviors, such as aggression, self-injury and temper tantrums (5).
- Stimulants: One such medication is Ritalin, which is commonly prescribed for attention deficit hyperactivity disorder (ADHD).
Some children with ASDs are treated with alternative therapies, such as a strict eating plan, vitamins and detoxification therapies (such as the drug treatment called chelation which reduces the amount of mercury and other metals in the body). To date, there is no evidence to show these treatments are helpful (17). Parents who are interested in alternative treatments should discuss the possible risks and benefits with their child’s health care provider.
The March of Dimes supports a number of grantees who are studying the role of specific genes in brain development for insight into how abnormalities may cause ASDs. Study results could provide the basis for developing new treatments for ASDs. Another grantee is studying differences in how autistic children process information and pay attention, in order to develop improved educational interventions.
- Autism Spectrum Disorders (U.S. Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities)
- Autism Fact Sheet (National Institute of Neurological Disorders and Stroke)
- Autism (American Academy of Pediatrics)
- Centers for Disease Control and Prevention (CDC). (2009). Autism spectrum disorders.
- Johnson, C.P., Myers, S.M. and the Council on Children with Disabilities. (2007). Identification and evaluation of children with autism spectrum disorders. Pediatrics, 120 (5), 1183-1215.
- Centers for Disease Control and Prevention (CDC). (2009). Prevalence of autism spectrum disorders – autism and developmental disabilities monitoring network, United States, 2006. Morbidity and Mortality Weekly Report, 58 (SS-10).
- Kogan, M.A., Blumberg, S.J., Schieve, L.A., Boyle, C.A., Perrin, J.M., et al. (2009). Prevalence of parent-reported diagnosis of autism spectrum disorder among children in the U.S., 2007. Pediatrics, 124 (5), 1395-1403.
- National Institute of Child Health & Human Development (2005). Autism Research at the NICHD.
- Limperopoulos, C., Bassan, H., Sullivan, N.R., Soul, J.S., Robertson, R.L., et al. (2008). Positive screening for autism in ex-preterm infants: prevalence and risk factors. Pediatrics, 121 (4), 758-765.
- Johnson, S., Hollis, C., Kochhar, P., Hennessy, E., Wolke, D., & Marlow, N. (2010). Autism spectrum disorders in extremely premature children. Journal of Pediatrics online.
- Kuban, K.C., O’Shea, T.M., Allred, E.N., Tager-Flusberg, H., Goldstein, D.J. & Leviton, A. (2009). Positive screening on the modified checklist for autism in toddlers (M-CHAT) in extremely low gestational age newborns. Journal of Pediatrics, 154 (4), 535-540.
- Buchmayer, S., Johansson, S., Johansson, A., Hultman, C.M., Sparen, P. & Cnattinguis, S. (2009). Can association between preterm birth and autism be explained by maternal or neonatal morbidity? Pediatrics, 124 (5), e817-825.
- Wang, K., Zhang, H., Ma, D., Bucan, M., Glessner, J.T., et al. (2009). Common genetic variants on 5p14.1 associate with autism spectrum disorders. Nature.
- Weiss, L.A., Shen, Y., Korn, J.M., Arking, D.E., Miller, D.T., et al. (2008). Association between microdeletion and microduplication at 16p11.2 and autism. New England Journal of Medicine, 358 (7), 667-675.
- Shelton, J.F., Tancredi, D.J. & Hertz-Picciotto. (2010). Independent and dependent contributions of advanced maternal and paternal ages to autism risk. Autism Research.
- Editors of The Lancet. (2010). Retraction—Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. The Lancet.
- Institute of Medicine. (2004). Immunization safety review: vaccines and autism. New York: National Academies Press.
- Schechter, R. & Grether, J. (2008). Continuing increases in autism reported to California’s developmental services system. Archives of General Psychiatry, 65 (1), 19-24.
- Dawson, G., Rogers, S., Munson, J., Smith, M., Winter, J., et al. (2010). Randomized, controlled trial of an intervention for toddlers with autism: the Early Start Denver model. Pediatrics, 125 (1), e7-e23.
- Myers, S.M., Johnson, C.P., and the Council on Children with Disabilities. (2007). Management of children with autism spectrum disorders. Pediatrics, 120 (5), 1162-1182.
Last reviewed May 2010
Frequently Asked Questions
Can dad's exposure to chemicals harm his future kids?
Dad's exposure to harmful chemicals and substances before conception or during his partner's pregnancy can affect his children. Harmful exposures can include drugs (prescription, over-the-counter and illegal drugs), alcohol, cigarettes, cigarette smoke, chemotherapy and radiation. They also include exposure to lead, mercury and pesticides.
Unlike mom's exposures, dad's exposures do not appear to cause birth defects. They can, however, damage a man's sperm quality, causing fertility problems and miscarriage. Some exposures may cause genetic changes in sperm that may increase the risk of childhood cancer. Cancer treatments, like chemotherapy and radiation, can seriously alter sperm, at least for a few months post treatment. Some men choose to bank their sperm to preserve its integrity before they receive treatment. If you have a question about a specific exposure, contact the Organization of Teratology Information Specialists at www.otispregnancy.org.
Can Rh factor affect my baby?
The Rh factor may be a problem if mom is Rh-negative but dad is Rh-positive. If dad is Rh-negative, there is no risk.
If your baby gets her Rh-positive factor from dad, your body may believe that your baby's red blood cells are foreign elements attacking you. Your body may make antibodies to fight them. This is called sensitization.
If you're Rh-negative, you can get shots of Rh immune globulin (RhIg) to stop your body from attacking your baby. It's best to get these shots at 28 weeks of pregnancy and again within 72 hours of giving birth if a blood test shows that your baby is Rh-positive. You won't need anymore shots after giving birth if your baby is Rh-negative. You should also get a shot after certain pregnancy exams like an amniocentesis, a chorionic villus sampling or an external cephalic version (when your provider tries to turn a breech-position baby head down before labor). You'll also want to get the shot if you have a miscarriage, an ectopic pregnancy or suffer abdominal trauma.
Does cleft lip or cleft palate cause dental problems?
A cleft lip or cleft palate that extends into the upper gums (where top teeth develop) can cause your baby to have certain dental problems, including:
- Missing teeth
- Too many teeth
- Oddly shaped teeth
- Teeth that are out of position around the cleft
Every baby with a cleft lip or palate should get regular dental checkups by a dentist with experience taking care of children with oral clefts. Dental problems caused by cleft lip or palate usually can be fixed. If needed, your baby can get ongoing care by a team of experts, including:
- A dentist
- An orthodontist to move teeth using braces
- An oral surgeon to reposition parts of the upper jaw, if needed, and to fix the cleft
See also: Cleft lip and cleft palate
Does cleft lip or cleft palate cause ear problems?
Cleft lip does not cause ear problems.
Babies with cleft palate, however, are more likely than other babies to have ear infections and, in some cases, hearing loss. This is because cleft palate can cause fluid to build up in your baby’s middle ear. The fluid can become infected and cause fever and earache. If fluid keeps building up with or without infection, it can cause mild to moderate hearing loss.
Without treatment , hearing loss can affect your baby’s language development and may become permanent.
With the right care, this kind of hearing loss is usually temporary. Your baby’s provider may recommend:
- Having your baby’s ears checked regularly for fluid buildup
- Medicines for treating fluid buildup and ear infections
- Ear tubes if your baby has fluid in his ears over and over again. Ear tubes are tiny tubes that are inserted into the eardrum to drain the fluid and help prevent infections.
See also: Cleft lip and cleft palate
Does cleft lip or cleft palate cause problems with breastfeeding?
Babies with only a cleft lip usually don’t have trouble breastfeeding. Most of the time, they can breastfeed just fine. But they may need some extra time to get started.
Babies with cleft lip and palate or with isolated cleft palate can have:
- Trouble sucking strong enough to draw milk through a nipple
- Problems with gagging or choking
- Problems with milk coming through the nose while feeding
Most babies with cleft palate can’t feed from the breast. If your baby has cleft palate, he can still get the health benefits of breastfeeding if you feed him breast milk from a bottle. Your provider can show you how to express (pump) milk from your breasts and store breast milk.
Your baby’s provider can help you start good breastfeeding habits right after your baby is born. She may recommend:
- Special nipples and bottles that can make feeding breast milk from a bottle easier
- An obturator. This is a small plastic plate that fits into the roof of your baby’s mouth and covers the cleft opening during feeding.
See also: Cleft lip and cleft palate, Breastfeeding
Does cleft lip or cleft palate cause speech problems?
Children with cleft lip generally have normal speech. Children with cleft lip and palate or isolated cleft palate may:
- Develop speech more slowly
- Have a nasal sound when speaking
- Have trouble making certain sounds
Most children can develop normal speech after having cleft palate repair. However, some children may need speech therapy to help develop normal speech.
See also: Cleft lip and cleft palate
What are choroid plexus cysts?
The choroid plexus is the area of the brain that produces the fluid that surrounds the brain and spinal cord. This is not an area of the brain that involves learning or thinking. Occasionally, one or more cysts can form in the choroid plexus. These cysts are made of blood vessels and tissue. They do not cause intellectual disabilities or learning problems. Using ultrasound, a health care provider can see these cysts in about 1 in 120 pregnancies at 15 to 20 weeks gestation. Most disappear during pregnancy or within several months after birth and are no risk to the baby. They aren't a problem by themselves. But if screening tests show other signs of risk, they may indicate a possible genetic defect. In this case, testing with higher-level ultrasound and/or amniocentesis may be recommended to confirm or rule out serious problems.
What if I didn't take folic acid before pregnancy?
If you didn’t take folic acid before getting pregnant, it doesn't necessarily mean that your baby will be born with birth defects. If women of childbearing age take 400 micrograms of folic acid every day before and during early pregnancy, it may help reduce their baby’s risk for birth defects of the brain and spin called neural tube defects (NTDs). But it only works if you take it before getting pregnant and during the first few weeks of pregnancy, often before you may even know you’re pregnant.
Because nearly half of all pregnancies in the United States are unplanned, it's important that all women of childbearing age (even if they're not trying to get pregnant) get at least 400 micrograms of folic acid every day. Take a multivitamin with folic acid before pregnancy. During pregnancy, switch to a prenatal vitamin, which should have 600 micrograms of folic acid.
Last reviewed November 2012