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The Placenta & Autism Connection

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It may sound incredibly early, but the American Academy of Pediatrics recommends doctors screen kids for autism at their 18-month checkup. The idea is that the sooner a child is diagnosed with an Autism Spectrum Disorder, the sooner therapy can begin. The drawback to screening at 18 months is that a year-and-a-half of post-birth brain growth has already happened. In other words, therapy at 18 months is, in some ways, already a late start.

Ideally, parents would know from birth that their child is on the spectrum. In reality, while there's not yet a way to know for sure, researchers may have found a method for determining those who are more at risk. The placenta holds some clues, according to a new study in the journal Biological Psychiatry.

RELATED: 10 Early Signs of Autism

Dr. Harvey J. Kliman, a research scientist in obstetrics, gynecology and reproductive sciences at the Yale School of Medicine, started looking into the placenta as an early sign of ASD risk after studying samples of the placentas of two boys who had autism. Trophoblast inclusions, or TIs, showed up when samples of both placentas were examined under a microscope. This prompted Kliman to conduct a more rigorous study of placentas and autism.

So he looked at samples from the placentas of 167 kids, 13 of whom had some form of autism. He found that TIs occurred at three times the rate in samples from kids with ASD, according to a report by the Los Angeles Times on the study.

Those results prompted yet another study of TIs in placentas. This time, they found 117 pregnant women who already had a child with autism, which meant their unborn child also had a higher risk of an ASD diagnosis. In fact, the placentas from those subsequent pregnancies were compared to the placentas from women who were not at this heightened risk. They found that 92 percent of this control group, the one with no known risks, had no TIs at all. Any that did had no more than two in the sample.

RELATED: A New Look at Autism

But the placentas of those higher-risk births had up to 15 TIs. Furthermore, only 59 percent showed no TIs in their samples. And those with more than two TIs in their sample had an eight-fold increase in risk of the child being diagnosed with autism. The researchers rejiggered the numbers to make the women in the control group most like the women in the high-risk group. Doing that multiplied the risk by 11.5 for those with more than two TIs present.

The study that would show conclusively that markers in the placenta predict risk for autism would not be feasible. That would require samples from every birth in a single hospital for a year, according to the LA Times, and then waiting 5 to 10 years to see if TI presence and frequency matched ASD diagnoses.

Still, with more studies, placentas could be seen as a way of showing risk and earlier screening tests developed for the very young.

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