"Contraceptives are never foolproof. Any act of intercourse between a fertile man and woman constitutes some risk of conception, no matter what contraceptives are used.... If 100,000 women who do not wish to become pregnant take the pill, three will probably die within the year and 1,000 will become pregnant. Under the present state of contraceptive failure, a woman does not have the option of remaining free of pregnancy by making careful use of contraceptives. She is at some risk in using the most effective methods of contraception available."