If you are trying to avoid pregnancy, abstinence and contraception are the only ways to greatly lessen the risk. Since it is very difficult to predict when ovulation will occur, having unprotected sex during the portion of your menstrual cycle when you are less likely to be ovulating (called the rhythm method) is not a reliable way to prevent pregnancy and results in many unplanned pregnancies. On the other hand, abstinence, or refraining from sex, is a good way to prevent pregnancy. Other reliable contraceptive methods include:

• Birth control pills, patches, implants, vaginal rings, or shots.
• Barrier methods such as contraceptive sponges, and male or female condoms and cervix covers like diaphragms and cervical caps (all must be used every time you have sex).
• Implantable intrauterine devices (IUDs).
• Sterilization methods such as tubal ligation for women and vasectomy for men.