The object of the study was to evaluate the research designs of social support interventions for prevention of low birth weight (LBW). A literature search of published articles identified 12 randomized controlled trials of social support to prevent LBW birth. These were evaluated using specific methodological criteria for effective intervention research. Only one study showed a significant reduction in LBW. However, none of the studies met all of the proposed criteria for rigorous intervention research. It is premature to conclude that social support interventions are ineffective in preventing LBW. Specific recommendations for future intervention research design are outlined.