Autism spectrum disorder is surely prevalent in the United States. In fact, about one in 68 kids have autism in the country, the Centers for Disease Control and Prevention reported.

Though the disorder is more popular in boys (one in 42 boys are diagnosed, compared to one in 189 girls), it is something that all races and ethnicities, from all classes of society, are facing, the CDC reported.

Most kids are diagnosed between 2 and 6 months old, research has found. Between 80 and 90 percent of kids show signs of autism before the age of 2, according to the CDC.

But sometimes it can go unnoticed.

Research by the Behavioural and Brain Sciences Unit at University College in London has found that some kids with low communication or social skills aren’t showing severe enough signs that they have autism. And those with autism have been known to have some special aptitudes. About 10 percent, according to WebMD, are proficient at memorization, drawing and conducting memory.

There are signs, though, of autism that you may be overlooking. Here are 14 of them you might not known about:

They don’t smile at people.
The Autism Science Foundation (ASF) reported that one of the biggest signs of someone having autism is not smiling at people. This is across several different age groups, from 2 month olds to even later in life.

They avoid eye contact.
This is especially prevalent for older adults, the Foundation found. In fact, they might not respond to any sound or interaction.

They have poor social skills.
People with autism will avoid eye contact and smiling at people, ultimately leading to poor social and communication skills, the foundation reported.

They can’t follow directions.
The ASF explained that if kids can’t follow “three-step directions,” they may also be showing signs of autism.

They have trouble pronouncing vowels.
The ASF explained that making vowel sounds — like “eh, ah, oh” — is a possible sign for having autism, especially for those who are 6 months old.

They don’t laugh.
This is especially true for those at least 6 months old, according to the ASF. This is a sign that they aren’t interacting well in social settings, which can be a big indicator of autism later on as a young adult.

They have trouble walking and crawling as a baby.
One-year-old kids who haven’t been crawling may have autism, the ASF reported. This is also true for those who are 4 months old and don’t “push down with legs when feet are placed on a hard surface,” the ASF explained.

They’re not talking, babbling or pointing.
Autism Speaks, an autism awareness organization, explained that one of the biggest “red flags” that someone may have autism is that they are having trouble speaking, pointing or even babbling on. This also depends upon age. If a child can’t put together a “meaningful, two-word” phrase by 24 months, that may be a sign of autism.

They have inconsistent emotions.
Kids who have sudden tempers, or are upset by the smallest things, might be revealing signs of having autism. If they don’t show fear, or seem overly worried, that’s also a possible sign, according to the CDC.

They talk, but not with regular tones.
Another sign of someone having autism is speaking with delayed speech, having poor language skills or even talking in a flat, monotone and robotic voice, the CDC reported.

They’re playing alone, and not in a creative way.
The CDC reported that kids who aren’t pretending — like they don’t “pretend to ‘feed a doll’” — and those who play alone may have autism.
They flap their hands or rock their body.
Children who are consistently flapping their hands or rocking their bodies back and forth may be showing signs of autism, too, according to WebMD.

They have trouble sleeping.
WebMD reported that 40 to 70 percent of people with autism have trouble sleeping. Bad sleeping habits, as well as odd eating habits, can also be signs of autism, the CDC said.

They don’t seek parental attention.
CBS News reported that kids with autism don’t “reach up when parents try to” pick them up, nor do they seek attention from their parents frequently.

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