HIV and men who have sex with men sexual activity with members of the same sex, regardless of how they personally identify themselves. Many MSM choose not to (or cannot for other reasons) identify as homosexual or bisexual. Similarly, the label excludes men who identify as gay or bisexual, but who have never had sex with another man, including many gay teenagers. The terms MSM and women who have sex with women (WSW) have been used in medical scholarship since at least 1990. But, the term has been attributed to Glick "et al.", because their usage in a 1994 study solidified the concept in medical terminology. MSM is
Men who have sex with men individuals who have compromised immune systems, especially HIV. Unprotected anal sex is a risk factor for formation of antisperm antibodies (ASA) in the recipient. In some people, ASA may cause autoimmune infertility. Many countries impose restrictions on donating blood for men who have or have had sex with men, as well as their female sexual partners—see the maps. Most national standards require direct questioning regarding a donor's sexual history, but the length of deferral varies. Men who have sex with men Men who have sex with men (MSM), also known as males who have sex with males, are male persons