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BackgroundA previous randomised study suggested that the progestagen, levonorgestrel, given alone in two separate doses each of 0.75 mg caused nausea and vomiting in fewer women and might be more effective than the Yuzpe regimen of combined oral contraceptives for emergency contraception, although the difference was not significant. We compared these two regimens when started within 72 h of unprotected coitus.MethodsWe enrolled in the double-blind, randomised trial 1998 women at 21 centres worldwide. Women with regular menses, not using hormonal contraception, and requesting emergency contraception after one unprotected coitus, received levonorgestrel (0.75 mg, repeated 12 h later) or the Yuzpe regimen (ethinyloestradiol 100 microg plus levonorgestrel 0.5 mg, repeated 12 h later).FindingsOutcome was unknown for 43 women (25 assigned levonorgestrel, 18 assigned Yuzpe regimen). Among the remaining 1955 women, the crude pregnancy rate was 1.1% (11/976) in the levonorgestrel group compared with 3.2% (31/979) in the Yuzpe regimen group. The crude relative risk of pregnancy for levonorgestrel compared with the Yuzpe regimen was 0.36 (95% CI 0.18-0.70). The proportion of pregnancies prevented (compared with the expected number without treatment) was 85% (74-93) with the levonorgestrel regimen and 57% (39-71) with the Yuzpe regimen. Nausea (23.1 vs 50.5%) and vomiting (5.6 vs 18.8%) were significantly less frequent with the levonorgestrel regimen than with the Yuzpe regimen (p

Human seminal plasma contains eight different prostaglandins belonging to the F series, i.e. PGF1 alpha, PGF2 alpha, 19-hydroxy-PGF1 alpha, 19-hydroxy PGF2 alpha, as well as the corresponding 8 beta-isomers. A systematic description of the mass spectrometric fragmentation of the 8 beta-isomers has not been previously reported. In the present study the prostaglandins were separated from human seminal plasma and analysed as methylester, trimethylsilylethers with gas chromatography mass spectrometry. All the eight F and 19-hydroxy F prostaglandins fragmented in the same manner, but the relative abundances of the formed ions varied in a typical way. Thus, the mass spectra of 8 beta-PGF1 alpha and 8 beta-19-hydroxy PGF1 alpha differed clearly from those of their 8 alpha-isomers, which could be used for identification and should be considered in selected ion monitoring. The ratio between the seminal plasma levels of 8 beta- and 8 alpha-isomers of 19-hydroxy F1 alpha was much higher than the corresponding ratio for the PGF1 alpha.