Table 2.1Percentage of women experiencing an unintended pregnancy during the first year of typical use and the first year of perfect use of contraception and the percentage continuing use at the end of the first year, United States

% of women experiencing an unintended pregnancy within the first year of use% of women continuing use at one year3
Method
(1)		Typical use1
(2)		Perfect use2
(3)		(4)
No method48585–
Spermicides5281842
Fertility awareness-based methods24–47
 Standard Days Method®6–5–
 TwoDay Method®6–4–
 Ovulation Method6–3–
 Sympto-thermal method–0.4–
Withdrawal22446
Sponge––36
 Parous women2420–
 Nulliparous women129–
Condom7
 Female21541
 Male18243
Diaphragm812657
Combined pill and progestin-only pill90.367
Evra patch90.367
NuvaRing®90.367
Depo-Provera60.256
Intrauterine devices
 Paragard® (copper T)0.80.678
 Mirena® (LNG)0.20.280
Implanon®0.050.0584
Female sterilization0.50.5100
Male sterilization0.150.10100
Emergency contraceptives: Emergency contraceptive pills or insertion of a copper-bearing intrauterine device after unprotected intercourse substantially reduces the risk of pregnancy.9

Lactational amenorrhea method: LAM is a highly effective, temporary method of contraception.10

Source: Trussell J. Contraceptive efficacy. In: Hatcher RA, Trussell J, Nelson AL, Cates W, Kowal D, Policar M, editors. Contraceptive technology: twentieth revised edition. New York (NY): Ardent Media; 2011. .

Notes:

1

Among typical couples who initiate use of a method (not necessarily for the first time), the percentage who experience an accidental pregnancy during the first year if they do not stop use for any other reason. Estimates of the probability of pregnancy during the first year of typical use for spermicides and the diaphragm are taken from the 1995 National Survey of Family Growth corrected for underreporting of abortion; estimates for fertility-awareness-based methods, withdrawal, the male condom, the pill and Depo-Provera are taken from the 1995 and 2002 National Survey of Family Growth corrected for underreporting of abortion. See the text for the derivation of estimates for the other methods (Trussell, 2011).

2

Among couples who initiate use of a method (not necessarily for the first time) and who use it perfectly (both consistently and correctly), the percentage who experience an accidental pregnancy during the first year if they do not stop use for any other reason. See the text for the derivation of the estimate for each method (Trussell, 2011).

3

Among couples attempting to avoid pregnancy, the percentage who continue to use a method for one year.

4

The percentages becoming pregnant in columns 2 and 3 are based on data from populations where contraception is not used and from women who cease using contraception in order to become pregnant. Among such populations, about 89% become pregnant within one year. This estimate was lowered slightly (to 85%) to represent the percentage who would become pregnant within one year among women now relying on reversible methods of contraception if they abandoned contraception altogether.

5

Foams, creams, gels, vaginal suppositories and vaginal film.

6

The Ovulation Method and TwoDay Method® are based on evaluation of cervical mucus. The Standard Days Method® avoids intercourse on cycle days 8–19. The sympto-thermal method is a double-check method based on evaluation of cervical mucus to determine the first fertile day and evaluation of cervical mucus and temperature to determine the last fertile day.

7

Without spermicides.

8

With spermicidal cream or jelly.

9

Plan B One-Step®, ella® and Next Choice One Dose® are the only dedicated products specifically marketed for emergency contraception in the United States at the time of writing. The label for Plan B One-Step (one dose is one white pill) says to take the pill within 72 hours after unprotected intercourse. Research has shown that all of the brands listed here are effective when used within 120 hours after unprotected sex. The label for Next Choice One Dose (one dose is one peach pill) says to take one pill within 72 hours after unprotected intercourse. The United States Food and Drug Administration has in addition declared the following 19 brands of oral contraceptives to be safe and effective for emergency contraception: Ogestrel® (one dose is two white pills), Nordette® (one dose is four light-orange pills), Cryselle®, Levora®, Low-Ogestrel®, Lo/Ovral®, or Quasence® (one dose is four white pills), Jolessa®, Portia®, Seasonale® or Trivora® (one dose is four pink pills), Seasonique® (one dose is four light-blue-green pills), Enpresse® (one dose is four orange pills), Lessina® (one dose is five pink pills), Aviane® or LoSeasonique® (one dose is five orange pills), Lutera® or Sronyx® (one dose is five white pills), and Lybrel® (one dose is six yellow pills).

10

However, to maintain effective protection against pregnancy, another method of contraception must be used as soon as menstruation resumes, the frequency or duration of breastfeeds is reduced, bottle feeds are introduced, or the baby reaches 6 months of age.

From: II, Using the recommendations

Cover of Medical Eligibility Criteria for Contraceptive Use
Medical Eligibility Criteria for Contraceptive Use. 5th edition.
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