We assessed exposure to blood during sex by asking respondents a series of questions about the lifetime frequency of engaging inhibitor manufacture in the following sexual behaviors: (1) having vaginal sexual intercourse when they or their partners had an injury involving bleeding (e.g., scratches or cuts); (2) scratching or biting their partners or being scratched or bitten by their partners so hard that it drew blood; (3) they or their partners bleeding as a result of engaging in rough sexual activity or sado-masochistic sexual activity in which 1 or both partners used whips, bondage, or other means of intentionally causing pain, injury, or bleeding; (4) engaging in anal sexual intercourse that caused pain or bleeding either to them or to their sexual partners; and (5) exposure to menstrual blood during sexual intercourse.

We used a 6-point scale to measure respondents�� bleeding and bleeding by their partners (scored 0�C5: 0 = never; 1 = once; 2 = 2�C4 times; 3 = 5�C10 times; 4 = 11�C50 times; and 5 = more than 50 times). The highest score of the responses to these questions was taken to indicate frequency of exposure to blood during sexual activity. We assessed exposure to sores while having oral sex by asking respondents how often in their lifetimes they had engaged in oral sex while either they or their sexual partners had a sore or raw area near the genitals or the mouth (e.g., split lip, gum disease, or cold sores). Again, we measured these behaviors separately for respondents and their partners with a 6-point scale (scored 0�C5: 0 = never; 1 = once; 2 = 2�C4 times; 3 = 5�C10 times; 4 = 11�C50 times; and 5 = more than 50 times).

The highest score of responses to these questions was taken to indicate level of exposure to sores during oral sex. To assess bleeding caused by intimate partner violence we used the revised conflict tactic scale22 to ask respondents about the frequency, since they were aged 14 years, of violence involving an intimate partner. The revised conflict tactic scale subscales included minor physical assaults (5 items), such as slapping or shoving; severe physical assaults (7 items), such as beating up or using a knife or gun; and injuries (6 items), such as needing to see a doctor or breaking a bone. Scales were assessed twice, for violence perpetrated by respondents and violence perpetrated by respondents�� partners.

Items were scored 0 to 7: 0 = never; 1 = once; 2 = 2�C5 times; 3 = 6�C10 times; 4 = 11�C20 times; 5 = 21�C50 times; 6 = 51�C100 times; and 7 = more than 100 times. Interviewers then listed aloud the types Cilengitide of intimate partner violence the respondents had just reported perpetrating and asked how frequently they had caused their partners to bleed. This question was repeated to assess the lifetime frequency of partners�� violence causing respondents to bleed. The higher score of the latter 2 questions was taken to indicate frequency of bleeding by respondents or their partners caused by intimate partner violence.