Preregistration study on the safety and contraceptive efficacy of a progesterone-releasing vaginal ring in Chilean nursing women

The contraceptive efficacy and safety of a progesterone-releasing vaginal r ing (PVR) manufactured in Chile were compared to that of the Copper T 380A IUD (T-Cu) in nursing women enrolled at three Chilean clinics. A total of 2 85 volunteers chose to use the PVR and 262 the T-Cu. Plasma progesterone le vels attained with the ring decreased from 25 to 24 nmol/L from month 1 to month 3 of use. Ring replacement was scheduled every 3 months. Volunteers c ontinued in the study until weaning or completing the continuous use of fou r PVRs. No pregnancies occurred in 2320 and 2183 woman-months of exposure w ith the PVR and the T-Cu, respectively. Lower continuation rates in the fir st 6 months because of problems with use and a longer lactational amenorrhe a were observed in the PVR than in the T-Cu group. Breast-feeding performan ce and infant growth were similar in both groups. These results confirm the high efficacy and safety of the PVR for nursing women and have led to the registration of the PVR by Chilean health authorities. CONTRACEPTION 1999;6 0: 9-14 (C) 1999 Elsevier Science Inc. All rights reserved.