Abstract: Although the positive effects of social networks on people’s health have been confirmed in research, studies on the mechanisms for such effects are rare. Some researchers argue that social networks promote health by encouraging people to indorse healthy behaviors. However, the proposed mechanism needs further empirical tests. Based on the data from a largescale questionnaire survey of more than 44 000 sampled households in 11 provinces in Western China, this study attempted to test the mechanism by which social networks influenced health. In contrast to the existing studies, this study didn’t examine the direct relationship between personal networks and his/her health. Rather, it targeted the mothers of newborns to investigate how their social networks influenced their decision of a healthy behavior of breastfeeding. Regardless of the fact that breastfeeding had generally been recognized as important to the health of both the infant and the mother, the result revealed that, among the mothers of newborns younger than 6 months in the Western provinces of China in 2004, only 22 percent provided exclusive breastfeeding to their children. Further analysis showed that social networks correlated significantly with an enhanced probability for mothers to breastfeed. If a new mother’s network had more strong ties, it was more likely to provide actual assistance and social support to the mother when the newborn was in early development stages; thus, the mother became more likely to breastfeed the infant. If mothers’ networks had health professionals, relevant knowledge and information would be effectively disseminated and the likelihood of breastfeeding would be raised. The current study tells us that social networks help improve people’s health primarily via their provision of social support and information for healthy behaviors.

Key words:  social networks, health, healthy behavior, mechanism, breastfeeding