Engaging in sex with a greater number of partners increases risk of contracting sexually transmitted diseases. A 1985 study found that 33 percent of male swingers and 10 percent of female swingers claimed to actively fear this risk.[41] In another study, sexually transmitted diseases topped the list of disadvantages of swinging, and 58 percent of swingers expressed some fear of HIV/AIDS.[2][42] Some couples have decided to drop out of open marriage lifestyles and become sexually monogamous in response to HIV/AIDS.[42][18]