Social networks and risk of neural tube defects.

The contribution of social support and social networks to risk of neural tube defects (NTDs) has not been explored, despite evidence that various aspects of the social environment contribute to their etiology. Using data from a population-based case-control study of deliveries occurring in California from 1989 to 1991, this study investigates whether social networks, as measured by the presence and frequency of various types of social contacts, are associated with NTD risk. In-person interviews were conducted with 538 (88% of eligible) mothers of NTD cases and with mothers of 539 non-malformed controls (88%) on average 5 months from the term delivery date. Unadjusted results indicate that women who reported having close friends, close relatives, or monthly contacts with close friends or relatives had 30-70% lower risks of having NTD-affected pregnancies, relative to women reporting 'none' to any of these measures. Only the presence of close friends was associated with reduced NTD risk after adjustment for other aspects of the social network and several potential covariates. This study is the first to investigate the association between social networks and risk of NTDs. Stronger inferences await replication and extension of these results.