Final answer:
The combined oral contraceptive pill has the strongest risk for DVT among contraceptive methods. The effectiveness of contraception varies based on the method and user compliance, with IUDs being among the most effective and fertility awareness among the least.
Step-by-step explanation:
The contraception with the strongest risk for deep vein thrombosis (DVT) is the combined oral contraceptive pill that contains both estrogen and progestin. The presence of estrogen in these pills can increase the coagulability of the blood, thereby elevating the risk of developing a blood clot in the deep veins, often in the leg, which can be dangerous. It's important for women to discuss their individual risk factors for DVT with their healthcare provider when choosing a contraceptive method.
Regarding the effectiveness of different contraception methods, it can be said that compliance with the contraceptive method is a key factor to their success or failure. In terms of typical effectiveness from least to most effective, the order would be: fertility awareness method (least effective), male condom, birth control pill, and IUD (most effective). A newly developed method of contraception with a 35 percent failure rate would not be considered very effective, as it means that 35 out of 100 couples using the method for a year would experience an unintended pregnancy.