Kids born in winters more likely to be autistic--study
POSTED May 8, 2011 - 12:20 | POSTED BY Yasser Ali
Last edited by Silky Chandvani on May 8, 2011 - 15:47
The risk could be as high as 16 percent for women conceiving in winter. Apparently, the risk peaks in winter after progressing through autumn to early spring.
The researchers looked at the birth records of over seven million children who were born in California in the 1990s and early 2000s. These birth records comprised about 91 percent of all the births in California between January 1990 and December 2002.
The rest of the birth records were not taken into consideration owing to inaccuracies in the records or because the children died before the age of six. It is usually when the children reach the age of six that they are diagnosed with autism. About 19,000 cases of autism were detected.
Ousseny Zerbo, key study author of the University of California report, said that the findings were quite pronounced even after adjusting for other factors like race/ethnicity, maternal education, and the year when the child was conceived.
Findings point to environmental factors
Findings of the research show a strong correlation between environmental factors and the onset of autism. The presence of seasonal viruses and the lack of vitamin D seem to be the key environmental factors.
The researchers compared the risk of conception in winter with the risk in summer. December, January, and February were taken as the months of winter. July was taken as the summer month.
It was found that the risk was 8 percent higher in winter months than it was for July. This risk rose to 16 percent when it was compared to March.
It is interesting to note that previous studies which attempted to link conception months with the risk of autism have come up with mixed results.
Past studies found mixed results
Studies done at Israel, Denmark, and Sweden had found that children conceived in March had the risk of getting autism. On the other hand, studies done in Canada, USA, and Japan revealed that those born in spring were at greater risk.
Nevertheless, all former studies had far smaller samples than the present study. The present study took into account millions of births and thousands of cases of autism.
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