Other new directions for women consist of variations on methods of delivery and for­mulations of hormones in existing methods. A spray-on contraceptive may be added to the choices of transdermal contraceptives, and a vaginal contraceptive ring used continuously for one year is under development (Harrison-Hohner, 2010). Some of the research on new contraceptive methods for women is focusing on nonhormonal

means of birth control, including a contraceptive vaccine, a vaginal ring, and vaginal spermicide with nonhormonal substances that block sperm motility (Brown, 2008; Z. Williams et al., 2006). Possible new designs for IUDs include a reversible plug in the oviduct that has been shown to be effective in preventing pregnancy in rabbits and has a high rate of pregnancy subsequent to removal (Wang et al., 2011).

Hoping to provide women with STI and HIV protection that is under their own control, researchers are studying spermicides that contain microbicides (substances that stop STI transmission; Kerns & Darney, 2011). Research with these gels also includes feedback from women about the consistency of gel that best enhances sexual pleasure (Littlefield, 2011). (See Chapter 15 for a discussion of microbicides.)

Since the advent of the pill, contraceptive options have greatly increased. However, the ideal of 100% effective, reversible contraceptives for men and women—methods that also have no side effects and protect against sexually transmitted infections—will, unfortunately, not be available anytime in the foreseeable future.