DAVIS, Calif., May 10 (UPI) -- A study involving 6.6 million California children in the 1990s and 2000s linked the month a child is conceived and the risk of autism, researchers say.
Lead study author Ousseny Zerbo, a fifth-year doctoral student at the University of California, Davis, School of Medicine, says researchers used records of children born from January 1990 through December 2002 from the state of California Office of Vital Statistics.
The study, published in the journal Epidemiology, found children conceived during winter -- for the study considered to be the months of December, January and February -- had a significantly greater risk of autism. Each month was compared with July, with an 8 percent higher autism incidence in December, increasing to 16 percent higher in March.
Children conceived in March had a 16 percent greater risk of later autism diagnosis when compared with July conceptions, the study said.
Zerbo and colleagues said the finding suggests environmental factors such as exposure to seasonal viruses like influenza might play a role in the higher risk of autism among children conceived during winter.
