A surprising number of African-Americans believe the government is trying to keep them in check through birth control. Public health researchers Sheryl Thorburn of Oregon State University and Laura M. Bogart of Rand Corporation surveyed 500 African-Americans across the U.S. They found that 34 percent agreed that “whites want to keep the numbers of black people down.” And 14 percent thought that “the government is trying to limit the black population by encouraging the use of condoms.”

Many of the respondents also believed government and health care organizations are lying about the side effects of birth-control methods. Together these views may make African-Americans less likely to use certain protective measures.

Although the beliefs may sound extreme, “these are things we can’t ignore,” Thorburn says, not least because condoms are effective at preventing transmission of HIV. She notes that conspiracy fears “do not occur in a vacuum.” Early in American history, white slave owners tried to control the fertility of black women for their own profit. Government programs to encourage the sterilization of black women persisted in back offices until the 1970s. And even though decades have passed and there is no credible evidence for a current conspiracy, African-American communities may still harbor simmering suspicion about institutional racism.

The study found that women holding conspiracy beliefs were not less likely to use birth control than others but were less likely to use the most effective methods, such as hormone pills, which involve visits to health care providers. To overcome suspicion, Thorburn recommends that pregnancy prevention programs specifically address conspiracy beliefs. She adds that community-based groups such as churches may be most successful in spreading trusted advice.