--- title: Autism Starts During Pregnancy description: A new report shows the brains of autistic children, who suffer from the disorder tied to a combination of contributing factors from genes to the environment, have differences in regions that develop during the mother's second trimester of pregnancy canonical: https://time.com/38717/autism-starts-during-second-trimester-of-pregnancy/ author: Alice Park article:opinion: false article:content_tier: free article:published_time: 2014-03-26T21:00:48.000Z article:modified_time: 2026-02-21T06:58:36.845Z article:section: Health og:title: Evidence that autism starts during pregnancy og:description: A new report shows the brains of autistic children, who suffer from the disorder tied to a combination of contributing factors from genes to the environment, have differences in regions that develop during the mother's second trimester of pregnancy og:url: https://time.com/38717/autism-starts-during-second-trimester-of-pregnancy/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt635fd8b31e70da02/6986877c810bbb03a4c90b3f/185274506.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 1500 og:image:height: 844 og:image:alt: pregnant og:type: article twitter:card: summary_large_image twitter:title: Evidence that autism starts during pregnancy twitter:description: A new report shows the brains of autistic children, who suffer from the disorder tied to a combination of contributing factors from genes to the environment, have differences in regions that develop during the mother's second trimester of pregnancy twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt635fd8b31e70da02/6986877c810bbb03a4c90b3f/185274506.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Autism Can Start During Second Trimester of Pregnancy > Sponsored content. 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Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators.  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Mar 26, 2014 9:00 PM UTC  Holding her future Holding her future Getty Images  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Mar 26, 2014 9:00 PM UTC While autism is almost certainly the result of a combination of contributing factors, from [genes](http://healthland.time.com/2013/01/15/new-gene-variants-linked-to-autism/) to [environmental exposures](http://healthland.time.com/2011/07/05/study-environmental-factors-may-be-just-as-important-as-genes-in-autism/) such as [pollution](http://time.com/25424/growing-evidence-that-autism-is-linked-to-pollution/), scientists say some of those influences may start during pregnancy. In a report published in the _New England Journal of Medicine_, researchers found that the brains of autistic children showed differences in certain regions that normally develop in the second trimester of pregnancy. Working with autopsy brains of 11 children with autism and 11 children without the disorder who were between the ages of two and 15 years, the scientists focused on 25 genes responsible for specific nerve cell types in the outer layer for the brain, what’s known as the cortex. **MORE:** [Autism Rises: More Children than Ever Have Autism, but Is the Increase Real?](http://healthland.time.com/2012/03/29/autism-rises-more-u-s-children-than-ever-have-autism-is-the-increase-real/) “The outcome was fascinating,” says Ed Lein, one of the co-authors of the paper and an investigator at the Allen Institute for Brain Science. “The regions seemed to correspond to the functional symptoms of autism.” They found that genes that coded for certain excitatory neurons, for example, were not expressed as robustly as they should have been. And these cell disruptions were often in exactly the areas that correlate with autism symptoms – parts of the brain responsible for functions such as communication and interpreting social cues. **MORE:** [Brain Imaging Could Detect Autism Risk in Infants as Young as 6 Months](http://healthland.time.com/2012/02/17/brain-imaging-could-detect-autism-risk-in-infants-as-young-as-6-months/) In 10 of the 11 autism brains, the researchers found patches of abnormal gene expression, which they discovered in only one of the 11 control samples. And Lein says the disruption may actually be more widespread than he and his colleagues could document, since they only analyzed tiny pieces of the cortex. The changes very likely occur prenatally, said Lein, a developmental neurobiologist, since these parts of the cortex are generally laid down in the second trimester. That suggests that at least some of autism’s origins may emerge in the womb. But how these factors interact with other, environmental contributors isn’t known yet. **MORE:** [Behavior Therapy Normalizes Brains of Autistic Children](http://healthland.time.com/2012/10/26/behavior-therapy-normalizes-brains-of-autistic-children/) It’s also unclear whether the autistic brains were deficient in the cells that expressed the genes in question, or whether the cells were there but not functioning properly. Figuring that out could lead to new potential treatments or even reversing the changes. “In principle, this could lead to earlier diagnosis and allow us to take advantage of normal parts of the cortex to rewire the brain with appropriate early behavioral interventions,” says Lein. Some studies already suggest that such behavior therapies, if begun early enough, [can change the brains of autistic children](http://healthland.time.com/2012/10/26/behavior-therapy-normalizes-brains-of-autistic-children/) to become more similar to those of normal children. What the current study confirms is that it’s never too early to start. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/38717/autism-starts-during-second-trimester-of-pregnancy/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/38717/autism-starts-during-second-trimester-of-pregnancy/"},"headline":"Autism Can Start During Second Trimester of Pregnancy","datePublished":"2014-03-26T21:00:48.000Z","dateModified":"2026-02-21T06:58:36.845Z","description":"A new report shows the brains of autistic children, who suffer from the disorder tied to a combination of contributing factors from genes to the environment, have differences in regions that develop during the mother's second trimester of pregnancy","url":"https://time.com/38717/autism-starts-during-second-trimester-of-pregnancy/","keywords":["Autism","autistic"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/blt635fd8b31e70da02/6986877c810bbb03a4c90b3f/185274506.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Alice Park","jobTitle":"Senior Correspondent","url":"https://time.com/author/alice-park/"}],"articleSection":"Health","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/blt635fd8b31e70da02/6986877c810bbb03a4c90b3f/185274506.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"pregnant","caption":"pregnant","creditText":"Getty Images","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"https://time.com/38717/autism-starts-during-second-trimester-of-pregnancy/","name":"Autism Can Start During Second Trimester of Pregnancy"}}]}] ```