Modifications of the Yuzpe Regimen of Emergency Contraception: Results of a Randomized Controlled Trial in Five Centers

Anne Webb, Abacus Centre for Contraception and Reproductive Health
Kelly Blanchard, Population Council
Alison Bigrigg, Glasgow Centre for Family Planning and Sexual Health
Sue Haskell, Planned Parenthood of Greater Iowa
Margaret Evans, Abacus Centre for Contraception and Reproductive Health
Sue Fernden, Planned Parenthood of Greater Iowa
Claire Leadbetter, Abacus Centre for Contraception and Reproductive Health
Aileen Spears, Glasgow Centre for Family Planning and Reproductive Health
Karen Johnstone, Glasgow Centre for Family Planning and Reproductive Health
Tara Shochet, Princeton University

Emergency contraceptives can prevent unintended pregnancy after unprotected intercourse. The most popular regimen ("Yuzpe") consists of ordinary combined oral contraceptives containing levonoregestrel/ethinyl-estradiol. Women traditionally take one dose within 72 hours of unprotected intercourse, and a second dose 12 hours later. We tested three simplifications of the standard regimen to explore its flexibility. Women presenting up to 72 hours after unprotected intercourse were randomized to receive: 1) standard two-dose Yuzpe, 2) a variant of Yuzpe that substituted norethindrone for levonorgestrel, or 3) the first dose of Yuzpe, followed 12 hours later by placebo. In a simultaneous observational study, we offered Yuzpe to women presenting 72-120 hours after unprotected intercourse, but declining copper IUDs. We found that oral contraceptive formulations containing norethindrone/ethinyl-estradiol work approximately as well as the standard combined regimen. Eliminating the second dose halves vomiting; it lowers efficacy somewhat, but not significantly. The regimen's 72-hour treatment cut-off appears needlessly restrictive.