It means that, if 100 women had unprotected intercourse once, during the second or third week of menstrual cycle, 8 of them would be likely to become pregnant, but that only 2 would become pregnant (a reduction of 75%) after use of the Yuzpe method.
A single dose of 1.5 mg of levonorgestrel appears to be as effective as the standard 2-dose levonorgestrel regimen.
Because it is difficult to determine the infertile time of the cycle with certainty, EC should be provided to a woman who is concerned about her risk of pregnancy regardless of the cycle day of exposure .
The effect of ECP use in women already pregnant on the outcome of pregnancy is unknown, but pregnancies in which the fetus has been exposed to oral contraceptives (OCs) have shown no evidence of teratogenicity .
The antiemetic meclizine has been shown to reduce the risk of nausea when taken orally in a dose of 50 mg 1 hour before the first dose of the Yuzpe method, but its use increases the incidence of drowsiness.
Although theoretically the serum concentrations of the ECP hormones are affected by the use of drugs such as rifampicin and certain anticonvulsants, the efficacy of ECPs in this situation is uncertain .