Among the following statements about different methods of birth control, which is not true? spermicides, used on their own without a barrier method such as a diaphragm, effectively prevent pregnancy because the chemicals kill all the millions of sperm released in the male’s ejaculation. hormonal methods, such as the pill, change a woman's hormone levels to prevent pregnancy, and in general are highly effective. male and female condoms offer protection against stds because they limit both the transmission of body fluids and direct genital skin-to-skin contact. surgical sterilization procedures, including a vasectomy for men and tubal ligation for women, must be given careful advance thought because they are meant to be permanent.