Bacterial vaginosis associated with increased risk of female-to-male HIV-1 transmission: In general, it was asserted that polyurethane condoms were more prone to breakage and slippage, and this delayed the approval by the U. It is important to emphasize that a person could become infected from having unprotected sex once or a person could have unprotected sex many times and not become infected, regardless of how low or high the risk per exposure is. Studies have repeatedly demonstrated that certain sexual practices are associated with a higher risk of HIV transmission than others. The latter was allowed because anal intercourse was considered equivalent to vaginal intercourse in this way; men were said to "take it like a woman" muliebria pati, "to undergo womanly things" when they were anally penetrated, but when a man performed anal sex on a woman, she was thought of as playing the boy's role. Studies of latex condom performance during human use reported breakage and slippage rates varying from 1. However, all studies that have controlled for competing risk behaviors 35,36,38,40,69,70 have concluded that oral-vaginal sex is extremely low risk. There are two ways that we talk about anal intercourse: Greek artwork of sexual interaction between men and boys usually depicted fondling or intercrural sex , which was not condemned for violating or feminizing boys,  while male-male anal intercourse was usually depicted between males of the same age-group. However, studies conducted in developing countries have estimated that per-act transmission probabilities are greater by a factor of 10 44,64 for both male-to-female and female-to-male transmission. But most experts agree that fellatio blow jobs is not an efficient route of HIV transmission. All studies on condom efficacy in the United States were conducted with heterosexual couples performing vaginal sex. For example, besides the risk of HIV transmission being higher for anal intercourse than for vaginal intercourse,    the risk of injury to the woman during anal intercourse is significantly higher than the risk of injury to her during vaginal intercourse because of the durability of the vaginal tissues compared to the anal tissues.