The U.S. Food and Drug Administration prohibits blood donations from all men who have sex with men (MSM), regardless of their HIV-negative status or their abstinence from sex. This lifetime ban denies a significant amount of donations, according to a study by The Williams Institute on Sexual Orientation and Gender Identity Law and Public Policy at UCLA School of Law.

The study estimates that a complete lifting of the ban would likely result in 360,600 MSM donating 615,300 pints of blood each year, which would increase the total annual blood supply in the United States by 2 percent to 4 percent, according to a Williams Institute statement. Such an increase could help save the lives of more than 1.8 million people nationwide each year.

Canada and the United Kingdom have revised their gay blood bans in recent years. Canada now prohibits blood donations only from MSM who have not been abstinent from sex for at least five years. The U.K. rules now have a one-year deferral for MSM. Mexico has established its criteria for blood donations on risk factors for transmission of blood-borne diseases.

Advocates are urging such changes in the United States. A five-year deferral would result in 172,000 MSM donating 293,400 pints each year. A one-year deferral would result in 185,800 MSM donating 317,000 pints annually.