OBJECTIVETo investigate the environmental risk factors for autism spectrum disorders (ASD) in children.

METHODSIn this case-control study, 81 boys with ASD, 74 boys with global developmental delay (GDD), and 163 healthy boys were enrolled. A self-designed nurturing environment questionnaire was used to record general demographic data, family social-economic status, parents' living habits and environmental exposure, maternal health status during pregnancy, birth situations, and rearing environment after birth. Multivariate logistic regression was used to identify environmental risk factors for ASD and GDD.

RESULTSMultivariate logistic regression analysis showed that six environmental risk factors such as maternal occupational toxicant exposure, diseases during pregnancy and a history of passive smoking, children's birth places, the frequency of outdoor activities in the second year after birth, and the opportunities to communicate with other age-matched children were significantly associated with the incidence of ASD (OR=20.67, 3.559, 2.422, 2.646, 23.820, and 5.081, respectively; P<0.05). Among the above six risk factors, passive smoking during pregnancy, the opportunities to communicate with their peers, and the frequency of outdoor activities in the second year after birth were also significantly associated with the incidence of GDD (P<0.05).

CONCLUSIONSMaternal occupational toxicant exposure, diseases during pregnancy, and low level of children's birth places may be the specific risk factors associated with ASD, and passive smoking during pregnancy, fewer opportunities to communicate with their peers, and fewer outdoor activities in the second year after birth are non-specific risk factors for ASD, indicating that the development of ASD may be influenced by both genes and environmental factors.