Effectiveness of Norplant implants through seven years: a large-scale study in China.
The effectiveness of Norplant implants over a seven year period of continuous use was studied in a multicenter trial. Pregnancy rates were 0.4 per 100 in both year six and year seven. More than 3,600 women completed 6 years and more than 2,400 women completed 7 years. Pregnancy rates increased with weight (p < .05) and decreased with age, but in years 6 and 7 combined, the pregnancy rate neither reached nor exceeded 1 per 100 woman years in any 5 year age group or in any 10 kg weight group.
Gu
S
S
Beijing Municipal Research Institute for Family Planning.
Sivin
I
I
Du
M
M
Zhang
L
L
Ying
L
L
Meng
F
F
Wu
S
S
Wang
P
P
Gao
Y
Y
He
X
X
D000328:Adult; D000367:Age Factors; D001835:Body Weight; D002681:China; D015331:Cohort Studies; D004343:Drug Implants; D005260:Female; D006801:Humans; D016912:Levonorgestrel / Q000008:administration & dosage / Q000592:standards*; D015993:Life Tables; D011247:Pregnancy; D018873:Pregnancy Rate; D013997:Time Factors
D004343:Drug Implants; D016912:Levonorgestrel