A Study to Evaluate the Contraceptive Effectiveness during the Third, Fourth and Fifth Year of Sino-implant (II)Use and the Pharmacokinetics (PK) over Five Years of use in Chinese Women~Population: A total of 590 Chinese Sino-Implant (II) users between 20and 44 years of age enrolled in one of four prospective cohorts:~Cohort 1: n=20 women with insertion dates 3-5months prior to enrollment and followed for 2-6 months Cohort 2:n=20 women with insertion dates 9-11 months prior to enrollment and followed for 2-6 months Cohort 3: n=250 women with insertion dates 21-24 months prior to enrollment and followed through month 36 Cohort 4:n=300 women with insertion dates 33-36 months prior to enrollment and followed through month 6~Study Duration: 33 total months in the field: 3 months of participant recruitment(all cohorts); up to 27 months of pregnancy monitoring and PK blood sampling in Cohort 4 (up to 15 months in Cohort 3 and 6 months in Cohort 1 and Cohort 2);and 3 months of close-out activities.~For secondary PK outcomes, blood samples will be taken 2 to 6 months apart from each woman in Cohort 1 and Cohort 2; at enrollment, month 30 and month 36 from the first 20 consenting women in Cohort 3; and at enrollment and months 42, 48, 54, and 60 from the first 30 consenting women in Cohort 4.~Primary Objective: To evaluate the contraceptive effectiveness of Sino-implant (II) during the third and fourth years of use~Secondary Objectives:~To evaluate the contraceptive effectiveness of Sino-implant (II) during the fifth year of use.~To characterize the total and free levonorgestrel (LNG) plasma concentration-time profiles over five years following Sino-implant (II) insertion~To characterize the sex hormone binding globulin (SHBG) serum concentration-time profile and its relationship to total LNG levels over five years following Sino-implant (II) insertion
A cohort study to Evaluate the contraceptive effectiveness of Sino-implant (II) during the 3rd and 4th years of use in Chinese women