How can monogamy help to prevent transmission of STDs?

Because sexually transmitted diseases (STDs) pass between partners during genital or oral intercourse, the number of sexual partners can affect your chances of contracting them. If you are active with only one partner, you risk contracting a STD only from that partner. If the partner is mutually monogamous and is negative for any STDs at the time of your sexual relationship, your risk is far lower to contract an STD.