Extended use of a progesterone-releasing vaginal ring in nursing women: a phase II clinical trial

This study evaluates the performance of extended use of a progesterone (P)-releasing vaginal ring (PVR) in nursing women. An open-label, noncomparative study on the safety and contraceptive efficacy of PVR replaced every 4 months of use (instead of 3 months) in 192 PVR acceptors. PVR use was initiated at day 59±2 (mean±SD) postpartum and continued until weaning or completing the use of three PVRs. Plasma P levels attained with the ring decreased from 17±1 to 14±1 nmol/L (mean±SE) from the third to the fourth month of use. These levels are still over the critical level of 10 nmol/L required for contraceptive protection. One pregnancy occurred in the third month of use of the second ring in 1998 woman-months of exposure. Extended use of the ring did not appear to affect breast-feeding performance or the rate of infant growth, and lactational amenorrhea was prolonged. No differences in the characteristics of bleeding between the third and fourth month of ring use were observed. The results indicate that use of the PVR for 4 months represents a safe and effective contraceptive for nursing women.