Infant boys exposed to high levels of the male hormone testosterone before birth have double the risk for language delay as females, according to a new study.
"An estimated 12% of toddlers experience significant delays in their language development," said study lead author Professor Andrew Whitehouse at the University of Western Australia. "While language development varies between individuals, males tend to develop later and at a slower rate than females."
The study appears in the Journal of Child Psychology and Psychiatry.
The Australian researchers noted that male foetuses have 10 times the levels of testosterone than females, which could explain the greater likelihood of language delays.
The study used the umbilical cord blood of 767 newborns to measure how much testosterone the infants were exposed to during a critical phase of brain development. The children's language ability was then assessed by the time they were 1, 2 and 3 years old.
The researchers found that male infants with high testosterone levels were two to three times more likely to have a language delay than females. In contrast, girls exposed to high testosterone levels had a lower risk for the developmental problem.
"Language delay is one of the most common reasons children are taken to a pediatrician," Whitehouse said in a journal news release. "Now these findings can help us to understand the biological mechanisms that may underpin language delay, as well as language development more generally."
While the study found an association between testosterone levels and language delays, it did not prove a cause and effect.
(HealthDay News, January 2012)
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