Autism is significantly more common in boys than in girls. This skewed sex ratio has been recognized since the first cases of autism were described in the 1940s. The exact reasons for the ratio remain unclear. It could be rooted in biological differences between the sexes. Or, some experts say, it may be an artifact of the way autism is defined and diagnosed.
Here’s how researchers estimate and explain the sex ratio in autism.
What is the sex ratio for autism?
Researchers have consistently found more boys than girls with autism when estimating the condition’s prevalence. This has been true regardless of whether the data came from parent-reported diagnoses, reviews of school and medical records, or diagnostic evaluations of children.
The most comprehensive analysis of autism’s sex ratio, published in 2017, drew on data from 54 prevalence studies worldwide. That analysis estimated about 4.2 boys with autism for every girl.
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