Contraceptive Effectiveness

The table below shows the percentageof women in the United States experiencing an unintended pregnancy during the firstyear of typical use and the first year of perfect use of contraceptionand the percentage continuing use at the end of the first year.

 

 
% of WomenExperiencing 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)
Chance4 85 85  
Spermicides5 26 6 40
Periodic abstinence 25   63
   Calendar   9  
   Ovulation method   3  
   Sympto-thermal6   2  
   Post-ovulation   1  
Withdrawal 19 4  
Cap7
   Parous women 40 26 42
   Nulliparous women 20 9 56
Sponge
   Parous women 40 20 42
   Nulliparous women 20 9 56
Diaphragm7 20 6 56
Condom8
   Female (Reality) 21 5 56
   Male 14 3 61
Pill 5   71
   Progestin only   0.5  
   Combined   0.1  
IUD
   Progesterone T 2.0 1.5 81
   Copper T 380A 0.8 0.6 78
   LNg 20 0.1 0.1 81
Depo-Provera 0.3 0.3 70
Norplant and Norplant-2 0.05 0.05 88
Female sterilization 0.5 0.5 100
Male sterilization 0.15 0.10 100
Emergency Contraceptive Pills: Treatment initiated within 72 hours after unprotected intercourse reduces the risk of pregnancy by at least 75%.9

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

Source: Trussell J. Contraceptiveefficacy. In Hatcher RA, Trussell J, Stewart F, Cates W, StewartGK, Kowal D, Guest F, Contraceptive Technology: SeventeenthRevised Edition. New York NY: Irvington Publishers, 1998,in press.
Notes:

1 Among typicalcouples who initiate use of a method (not necessarily for thefirst time), the percentage who experience an accidental pregnancyduring the first year if they do not stop use for any other reason.

2 Among coupleswho 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 thefirst year if they do not stop use for any other reason.

3 Among couplesattempting to avoid pregnancy, the percentage who continue touse a method for one year.

4 The percentsbecoming pregnant in columns (2) and (3) are based on data frompopulations where contraception is not used and from women whocease using contraception in order to become pregnant. Among suchpopulations, about 89% become pregnant within one year. This estimatewas lowered slightly (to 85%) to represent the percent who wouldbecome pregnant within one year among women now relying on reversiblemethods of contraception if they abandoned contraception altogether.

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

6 Cervical mucus(ovulation) method supplemented by calendar in the pre-ovulatoryand basal body temperature in the post-ovulatory phases.

7 With spermicidalcream or jelly.

8 Without spermicides.

9 The treatmentschedule is one dose within 72 hours after unprotected intercourse,and a second dose 12 hours after the first dose. Preven is the only dedicated product marketed for emergency contraception in the United States (1 dose is 2 blue pills). The Food andDrug Administration has declared the following brands of oralcontraceptives to be safe and effective for emergency contraception:Ovral (1 dose is 2 white pills), Alesse or Levlite (1 dose is 5 pink pills),Nordette or Levlen (1 dose is 4 light-orange pills), Lo/Ovral or Levora(1 dose is 4 white pills), Trivora (1 dose is 4 pink pills), Triphasil or Tri-Levlen (1 dose is4 yellow pills).

10However, to maintain effective protection against pregnancy, anothermethod of contraception must be used as soon as menstruation resumes,the frequency or duration of breastfeeds is reduced, bottle feedsare introduced, or the baby reaches six months of age.

If you have questions about emergency contraception, please visit our page on frequently asked questions.