Berger G S, Taylor R N, Treloar A E
Int J Gynaecol Obstet. 1977;15(2):125-7. doi: 10.1002/j.1879-3479.1977.tb00660.x.
Menstrual cycle lengths prior to and after oral contraceptive use were prospectively recorded for 245 women. In this preliminary study, a difference in the distributions in the pre- and post-pill cycle lengths was observed. An increase of 5 days in the medial cycle length occurred after oral contraceptive use had been discontinued. Although there was an approximately twofold relative risk of amenorrhea of 90 days' duration or more after discontinuing pill use, the differences in the rates of amenorrhea between the pre-pill and post-pill cycles were not statistically significant.
前瞻性记录了245名女性在使用口服避孕药前后的月经周期长度。在这项初步研究中，观察到服药前和服药后周期长度的分布存在差异。停用口服避孕药后，平均周期长度增加了5天。尽管停药后出现持续90天或更长时间闭经的相对风险约为两倍，但服药前和服药后周期的闭经率差异无统计学意义。
