Boys with autism tend to be born smaller than typical peers – but then have faster growth and overtake them by the age of three, according to a new study. On average they had smaller heads, were shorter and weighed less at birth. After that they put on a growth spurt.
The study, published in the Journal of the American Academy of Child and Adolescent Psychiatry, found that boys with autism developed significantly larger heads and longer, heavier bodies than their normally developing peers in the first two years after birth. These effects were not significant in girls.
Developmental Delays in Children with Autism
Other children with autism may appear to develop alongside their typically developing peers during infancy, but then slow, stop developing, or regress as they get older.
Children with autism tend to gain weight rapidly in infancy and to have high levels of the fat hormone leptin, according to a new study1. Other studies have tied rapid weight gain in infancy to autism.
On average, the boys with autism had a head circumference that was 1.2 centimeters smaller at birth than that of typical children. They were also about 4.8 centimeters shorter and about 0.2 kilograms lighter.
Autism doesn't get worse with age, but certain symptoms can become more pronounced and problematic as the child grows older and is more challenged.
People who carry certain mutations in gene CHD8, a gene strongly linked to autism, tend to be taller and have larger heads than the average person. They also tend to have intellectual disability, according to a study conducted by geneticists at Cedars-Sinai Medical Center in Los Angeles, California.
As a group, children with ASDs appear to be taller than their unaffected siblings. Children with Asperger's Syndrome and Autism, specifically, appear taller than those with PDD-NOS who, in turn, do not differ from unaffected siblings in height. (See Figure 1.)
About 85 percent of the children in each group walked independently by 18 months. But when researchers focused on children with IQs of around 50, they found that 60 percent of the children with intellectual disability, ADHD or language disorders walked by 18 months compared with 80 percent of those with autism.
Army crawling could be an early sign of autism, but this is not always the case. If an infant chooses to move about with just their arms, sliding across the floor, this could simply be a sign of neuro-diversity.
Role of Growth Charts
Many studies have found that from a tenth to a third of children with autism have unusually large heads.
Does The Father Or Mother Carry The Autism Gene? Autism was always thought to have a maternal inheritance component, however, research suggests that the rarer variants associated with the disorder are usually inherited from the father.
Research suggests that reduced or absent communication, including lack of response to their name, lack of gesturing, and language delays, are strong indicators of autism. For example: At 4 months of age , a baby should begin to make sounds, babble, or coo. At 6 months , babies often begin to respond to their name.
Autistic children can have particular sleep and settling problems, including: irregular sleeping and waking patterns – for example, lying awake until very late or waking very early in the morning. sleeping much less than expected for their age, or being awake for more than an hour during the night.
Excessive-Passivity. Lack of crying, lack of movement, and lack of interest in surroundings – often the baby seems comfortable, showing no sign of distress, hunger etc. Sleeping all night long during the initial months of life.
The country with the highest rate of diagnosed autism in the world is Qatar, and the country with the lowest rate is France. Around 4 times as many boys have autism as girls. The rate of autism in the U.S. went from 1 in 150 in 2000 to 1 in 100 in 2022.
Advances in diagnostic capabilities and greater understanding and awareness of autism spectrum disorder seem to be largely driving the increase, the Rutgers researchers said. But there's probably more to the story: Genetic factors, and perhaps some environmental ones, too, might also be contributing to the trend.
There are studies that suggest the average age of children diagnosed with autism is around three years old in both the United States (US) and in the United Kingdom (UK).
They were as long as their peers, but weighed about one-third of a pound to three-quarters of a pound less at age 3. Those differences don't simply mean that the girls were smaller and the boys were bigger, the researchers found.
Yes, some autistic people have a small head, or microcephaly, although this seems to be much less common than macrocephaly — and much less is known about it1.
Certain genetic variants are linked to a higher chance of a child being somewhere on the spectrum. Also, it takes fewer variants to predispose a boy to developing autism than it does a girl.