"It has long been known that autism is an umbrella term for a wide range of disorders that impair social and communication skills," said lead author Prof Amy Kalkbrenner from the University of Wisconsin-Milwaukee.
"What we are seeing is that some disorders on the autism spectrum, more than others, may be influenced by a factor such as whether a mother smokes during pregnancy," she was quoted by the 'Daily Mail' as saying.
For their study, the researchers looked at a population- based study comparing smoking data from birth certificates of hundreds of thousands of children from 11 states to a database of children diagnosed with autism.
