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Am J Obstet Gynecol. 2001 Mar;184(4):531-7.

Effectiveness of emergency contraceptive pills between 72 and 120 hours after unprotected sexual intercourse.

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Department of Family Medicine, University of Montreal, and the Local Center for Community Services, Laval, Quebec, Canada.



This article reopens the issue of a medical practice that has been well established for more than three decades by proposing an extension of the period during which treatment with the "morning-after" pill is currently prescribed. The objective is to determine the effectiveness of the regimen of Yuzpe and Lancee when it is administered between 72 and 120 hours after sexual intercourse.


We conducted an observational study comparing 2 groups of women for whom the regimen of Yuzpe and Lancee was administered after unprotected sexual intercourse. One group (usual time frame treatment group) sought consultation within 72 hours (n = 131), and the other (extended time frame treatment group) after 72 to 120 hours (n = 169).


The pregnancy rate was 0.8% for the <72-hour group and 1.8% for the 72- to 120-hour group. The effectiveness rate varied from 87% to 90% for the <72-hour group and from 72% to 87% for the 72- to 120-hour group. In both groups the chi(2) tests showed that emergency contraceptive pills significantly reduced the risk of pregnancy.


Women should be encouraged to seek consultation as quickly as possible after unprotected sexual intercourse. However, if the usual time limit (<72 hours) has expired, the so-called "morning-after" pill should be recommended if an intrauterine contraceptive device is not available. Emergency contraceptive pills have a favorable success rate after 72 hours, with a pregnancy rate that is significantly lower than would be expected if no contraceptive were administered.

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