How many autistic children are there currently living in the world?

The prevalence of autism has been increasing globally in recent years and it is currently estimated that around 1 in 54 children are living with the condition.

According to the Centers for Disease Control and Prevention (CDC) in the United States, the estimated prevalence of autism spectrum disorder (ASD) is 1 in 44 children aged 8 years in 2018. Globally, there are roughly 792 million children aged 0-14 years. Thus, using the US prevalence the world would roughly have:

792,000,000(estimated world child population )/44 = Approximately 18 million