Postcoital contraception with levonorgestrel during the peri-ovulatory phase of the menstrual cycle. Task Force on Post-ovulatory Methods for Fertility Regulation.
The contraceptive efficacy and side effects of postcoital levonorgestrel used repeatedly during the peri-ovulatory period of one cycle was examined in 259 women. All subjects were of proven fertility in their present union and had ovulatory cycles as assessed from pre-treatment BBT charts. The mean number of coital acts during the treatment cycle was 7.5 (SD:2.6) and the mean number of 0.75 mg levonorgestrel tablets taken during the peri-ovulatory period was 4.0 (SD:1.2). Two pregnancies, both considered to be method failures, occurred, giving a failure rate of 0.8% per treated cycle. Although the overall effect of levonorgestrel on menstrual cycle length was small and insignificant, menstrual cycle disturbances were not uncommon. Intermenstrual bleeding or spotting occurred in 8.5% of the treated cycles and 12.5% of the cycles were less than 20 or more than 35 days. Other side effects, mainly nausea, headache and dizziness, were reported by about 20% of the subjects but the apparent incidence of these complaints varied markedly between the nine participating centres from 0% to just over 50%. The data suggest that repeated postcoital use of levonorgestrel is probably not a viable approach to fertility regulation for the majority of women who have regular intercourse and wish to limit the number of their pregnancies.
D000328:Adult; D003281:Contraceptives, Postcoital / Q000008:administration & dosage*; D003282:Contraceptives, Postcoital, Hormonal / Q000008:administration & dosage* / Q000009:adverse effects; D004341:Drug Evaluation; D005260:Female; D006801:Humans; D016912:Levonorgestrel; D008597:Menstrual Cycle / Q000187:drug effects; D009644:Norgestrel / Q000008:administration & dosage* / Q000009:adverse effects; D010060:Ovulation / Q000187:drug effects*; D011247:Pregnancy
D003281:Contraceptives, Postcoital; D003282:Contraceptives, Postcoital, Hormonal; D009644:Norgestrel; D016912:Levonorgestrel