避孕的方法之一是使用避孕药物。避孕药物可以單独使用,也可以与避孕用具配合使用。单独使用时如果使用得当,可以达到避孕目的,如果与避孕用具一同使用,就更加安全可靠。使用者必須正确地遵照医囑或使用方法的指导,否則难免失敗。避孕药物的制备和选擇,也是成功的关鍵之一。好的避孕药应具有以下几个特点:一、杀灭精子的持續时间应保持在240分鐘以上,被体液稀釋后,仍具有功效。二、在人体内能借体温与陰道的分泌液完全融合,並能迅速扩散均匀。三、不过于濃稠,以致成膠冻狀而不融化;也不宜过于稀薄以致容易流出体外。四、对人体应 One of the ways of contraception is to use contraceptives. Contraceptives can be used alone or in combination with contraceptives. If used properly when used alone, the purpose of contraception can be achieved and, if used with contraceptives, it is more secure. The user must correctly follow the instructions of the doctor or the method of use, otherwise it will inevitably fail. The preparation and selection of contraceptives is also one of the keys to success. Good contraceptives should have the following characteristics: First, the duration of sperm should be maintained at 240 minutes or more, was diluted body fluids, still have efficacy. Second, in the human body can take the body temperature and vaginal secretion of fluid fully integrated, and can quickly spread evenly. Third, but thick, so as not to melt into a jelly; nor should it be too thin to easily flow out of the body. Fourth, the human body should be