The most effective methods of birth control are sterilization by means of vasectomy in males and tubal ligation in females, intrauterine devices (IUDs), and implantable birth control.[5] This is followed by a number of hormone-based methods including oral pills, patches, vaginal rings, and injections.[5] Less effective methods include physical barriers such as condoms, diaphragms and birth control sponges and fertility awareness methods.[5] The least effective methods are spermicides and withdrawal by the male before ejaculation.[5] Sterilization, while highly effective, is not usually reversible; all other methods are reversible, most immediately upon stopping them.[5] Safe sex practices, such as with the use of male or female condoms, can also help prevent sexually transmitted infections.[6] Other methods of birth control do not protect against sexually transmitted diseases.[7] Emergency birth control can prevent pregnancy if taken within the 72 to 120 hours after unprotected sex.[8][9] Some argue not having sex as a form of birth control, but abstinence-only sex education may increase teenage pregnancies if offered without birth control education, due to non-compliance.[10][11]