A detailed analysis of menstrual blood loss in women using Norplant® and Nestorone® progestogen-only contraceptive implants or vaginal rings

Changes to the pattern of menstrual bleeding are almost universal in women using progestogen-only methods of contraception, and are an important cause of discontinuation of these methods. The present study was designed to explore the changes in menstrual bleeding patterns and objectively measure menstrual blood loss (MBL) in 110 women before and during one year of use of 4 different progestogen-only contraceptives: Norplant subdermal levonorgestrel implants; Nestorone progestogen 4-cm or 6-cm implants nominally delivering 100 microg or 150 microg daily; or a vaginal ring (CVR) delivering 100 microg of Nestorone (NES) daily (CVR users were limited to only 6 months of use). Groups could not be directly compared because of the differences in numbers of subjects and durations of treatment. The total MBL during each of the three 8-week collection periods during treatment decreased significantly in each group compared to the total blood loss in the two control cycles (greater than 50% decrease in all groups during the first 6 months), although the differences between individual women at the extremes remained considerable. The highest blood loss measured on any single day during the treatment collection periods was significantly reduced (p0.001) in users of all four devices in all three collection periods compared to the control period (CVR users did not have a 3rd collection period). The Nestorone-releasing CVR was associated with an 88% reduction in mean MBL and a high incidence of amenorrhea at 6 months. There was considerable variation in percentage reduction in total blood loss at 6 and 12 months between individual women ranging from 100% (women with amenorrhea) to a small minority experiencing an increase compared with control cycles. The increases in measured blood loss during treatment were almost entirely in women with light bleeding in the control period and were related to prolonged episodes of light bleeding rather than heavy bleeding. Women contemplating use of a progestogen-only contraceptive method need to be counseled about alterations to the menstrual cycle but can be reassured that total blood loss will usually be much less than with normal cycles.