A study of 6.6 million California children born in the 1990s and 2000s found that the month of conception is linked to an increased risk of autism. Kids born in July had the lowest autism incidence, and those born in December, January, and February had an increasing risk up to March. Children conceived in that month had a 16% greater risk compared to July conceptions. The researchers say this suggests seasonal factors like exposure to the flu may contribute to later autism diagnosis.

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