Failure rates of common birth control methods: Symptom-based fertility awareness ("modern Natural Family Planning"): 1.8% Cervical cap: 6.7% Combined oral contraceptive pill: 8-9% Note: "Combined" oral contraceptive pills combine estrogen-based drugs with abortifacients. So without "undetected miscarriages" (i.e., dead babies), this rate would be higher. Ortho-Evra patch: 8-9% Nuva Ring: 8-9% Diaphragm: 12-16% (depending on source) Male Latex Condom: 15-18% (spermicide-treated, depending on source) Coitus Interruptus: 18-22% (depending on source) Rhythm Method: 24-25% (depending on source) Contraceptive Sponge: 24-32% (depending on whether the woman had been previously pregnant) Spermicide: 28% (without condom) Please note the following: > Condom use is...