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Table 174.1

First-year Failure Rates of Birth Control Methods

	Percentage of women who experience accidental pregnancy in the first year of use
Method	Lowest expected failure rate (%)^a	Failure rate in typical users (%)^b
Tubal ligation	0.2	0.4
Vasectomy	0.1	0.15
Injectable progestin	0.3	0.3
Combined birth control pills	0.1	3
Progestin-only pill	0.5	3
Intrauterine device
Copper T380A	0.8	3
Progestasert	2.0	—
Condom	2	12
Diaphragm	6	18
Sponge (with spermicide)	6–9	18–28
Cervical cap	6	18
Foams, creams, jellies, and vaginal suppositories	3	21
Coitus interruptus	4	18
Fertility awareness techniques (basal body temperature, mucus method, calendar, and "rhythm")	1–9	20
Douche	—	40
Chance (no method of birth control)	89	89

Designed to complete the sentence: "In 100 users who start out the year using a given method and who use it correctly and consistently, the lowest observed failure rate has been ———"

Designed to complete the sentence: "In 100 typical users who start out the year using a given method, the number of pregnancies by the end of the year will be ———" Many of the failure rates in this column were derived from Trussell J, Kost K. Contraceptive failure in the United States: A critical review of the literature. Stud Fam Plan 1987; 18(5):Table 1. Updated to reflect subsequent studies.