Individual blacks' racial backgrounds cover the entire spectrum, from virtually no European bloodline to nearly all European. Furthermore, a substantial percentage of African Americans have Native-American lineage, a factor the authors did not consider. To look for a genetic cause of the difference in birth weight between the races is premature until the sociocultural questions have been answered. This has not been done. Race very often serves as a proxy for poverty.
Medical sociologists recognize attitudinal and organizational barriers to health care.
Attitudinal barriers are those that prevent individual persons from becoming motivated to seek needed health services. Organizational barriers, in contrast, prevent motivated persons from obtaining the services they know they need. Examples of attitudinal barriers are cultural isolation, fatalism, customs, superstition, and fear. Examples of organizational barriers are lack of health insurance, lack of transportation, poor access to health care providers, a paucity of health care facilities, and the like. It is known that these barriers are greatest in minority communities.