Postcoital contraception: a family planning study
Kane, L.A.; Sparrow, M.J.
New Zealand Medical Journal 102(865): 151-153
1989
ISSN/ISBN: 0028-8446 PMID: 2649811 Document Number: 326518
The New Zealand Family Planning Association undertook a prospective study of Yuzpe's postcoital method of contraception (0.1 mg ethinyloestradiol and 1 mg d1-norgestrel taken within 72 hours of unprotected intercourse and repeated 12 hours later). The study also used pills containing levonorgestrel. Both pill formulations were equally effective. All participants were drawn from six family planning branches throughout the country. The study convered a period of one year. There were 909 participants with 8% lost to follow up. Strict criteria excluded women on medication or hormone therapy. The ages ranged from 11 to 43 years with 92% aged 19 years and under. Results revealed an overall failure rate of 2.3% and a significantly higher failure rate (4.49%) if the method was taken after 48 hours of unprotected intercourse and a significantly lower failure rate (1.22%) if taken before 12 hours of unprotected intercourse. Vomiting occurred in 17% but it did not affect the failure rate.