***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: A levonorgestrel-releasing IUD and the Copper T 380Ag IUD were in r and omized comparison for seven years in five clinics . In two other clinics the r and omized study was truncated at five years , but use of the Copper T continued . No pregnancies occurred to users of either device in years 6 and 7 . Cumulative pregnancy rates were 1.1 per 100 at seven years for the steroid-releasing and 1.4 per 100 for the copper-releasing IUDs .  Cumulative rates of PID did not differ between devices . Infection rates appeared to be lowest during the sixth and seventh years of the study . Termination attributable to amenorrhea was the principal contributor to differences in cumulative continuation rates between devices . At the five clinics that carried the comparative study to seven years , cumulative continuation rates were 24.9 per 100 for LNg20 IUD users and 29.4 per 100 for TCu 380Ag users . Women who used either method for periods of five to seven years experienced , on average , marked to mild increases in hemoglobin as compared with levels at admission . The Copper T380 family and the LNg20 IUDs represent the most effective reversible contraceptive methods yet studied in long-term r and omized trials IUDs releasing 20 mcg/day of levonorgestrel ( LNg20 ) were in r and omized trial together with the Copper T , model TCu 380Ag , in seven centers involving 2244 women . Two-year ( 25 months ) gross cumulative pregnancy rates were 0.2 + /- 0.2 and 0.9 + /- 0.3 for the levonorgestrel and copper releasing devices , respectively ( P greater than 0.05 ) . There were no ectopic pregnancies in more than 1600 woman-years of use of each device . Removal rates for bleeding and /or pain or for medical reasons other than menstrual problems did not differ significantly between devices . Oligomenorrhea or amenorrhea prompted 10.7 per hundred ( gross rate , 8.4 net rate ) women using the LNg 20 IUD to request removal in the two-year period , significantly above the 0.2 per hundred rate among women with the Copper IUD ( P less than 0.001 ) . At the end of two years an estimated 59.4 per 100 women were continuing use of the LNg 20 IUD , and 67.5 per 100 ( P less than 0.001 ) with the TCu 380Ag . This difference is almost wholly ascribable to a marked reduction in bleeding episodes and days among women using the LNg 20 device with concomitant removal of device . Hemoglobin rose an average of 0.5 g/dl ( P less than 0.001 ) for this group whereas women using the TCu 380Ag experienced a decline of 0.2 g/dl compared with baseline values ( P less than 0.001 ) A r and omized comparative performance study of two  levonorgestrel intrauterine devices ( IUDs )  and a copper ( Nova-T ) IUD  ( Leiras , Turku , Finl and ) was performed at two clinics in Finl and and one in Brazil . The 24-month cumulative event rates per 100 women are reported . Six thous and woman-months of use were recorded with the levonorgestrel IUD and 3000 with the Nova-T device .  Pregnancy rates at 2 years of use were 0.6 and 0 with the two levonorgestrel IUDs and 3.3 with the Nova-T IUD .  Removal rates because of bleeding and /or pain were low with all three IUDs : 7.5 , 7.6 , and 7.1 , respectively , at 24 months . Recordings of the number of days of bleeding showed significantly fewer days of bleeding during use of the levonorgestrel IUDs than the Nova-T IUD from the second month of use onward , until the end of the second year . No infections were recorded in association with use of the levonorgestrel IUDs , and only one termination because of infection was recorded for the Nova-T IUD . The continuation rates of use at 24 months were 66.6 , 60.7 , and 71.9 for the two levonorgestrel IUDs and the Nova-T IUD , respectively ; the differences were not statistically significant Data obtained from question naires on the occurrence of  dysmenorrhoea in women using IUDs inserted r and omly ( 146 of them Progestasert and 149 Copper 7 ) are analyzed . In both groups a reduction in the intensity of menstrual cramps was observed over 12 months of use . Although these reductions are significant in each group , they are slightly higher in Progestasert users . However , on comparing the reduction tendencies of both groups , the difference between them is not significant . No significant differences become apparent either when comparing premenstrual and intermenstrual camps . The usefulness of simple question naires directed at detecting the nature of pain in currently used family planning forms for IUD users is discussed A r and omized study was performed in two clinics in order to compare the efficacy , safety and acceptability of a new model of a levonorgestrel-releasing intracervical device situated either in the cervical canal ( group I ) or in the uterine cavity ( group II ) . Group I included 151 women ( age 18 - 43 ) and group II , 147 women ( age 19 - 43 ) . The number of nulliparous women was 145 . The total expulsion rate was 9.1 % . The expulsion rate was lower among nulliparous women ( 4.8 % ) than among parous women ( 13.1 % ) . There was also a significant difference in the expulsion rates between the two clinics . Two pregnancies occurred in both groups and two of these were ectopic , one in each group . The other two occurred after unnoticed expulsion . These figures give 12-month cumulative pregnancy rates of 1.3 % and 1.4 % in groups I and II , respectively . Total infection rate was 0.3 % . The continuation rates were 82.1 % in group I and 85.0 % in group II after the first year . At three-month follow-up there were significantly fewer menstrual problems in group I than in group II ( p = 0.0266 ) . It is concluded that expulsion is still a problem with a small device but it may be diminished by intrauterine insertion and by selecting the users carefully The clinical performance of two levonorgestrel-releasing intrauterine devices ( IUDs )  with different release rates was studied and compared with a copper-releasing Nova-T device in a r and omized partly double-blind multi clinical trial . Special attention was given to patterns of bleeding , hormonal side-effects , blood pressure and body weight . The clinical acceptability of the levonorgestrel IUDs was as good as that of the copper-releasing IUD . A highly significant decrease in the amount of menstrual blood loss was seen with the levonorgestrel-IUDs , the users of which experienced fewer days of bleeding than prior to insertion . Patients suffering from dysmenorrhea experienced relief from this symptom after insertion of a levonorgestrel-IUD . Some side-effects , usually referred to as hormonal , increased during the levonorgestrel-IUD use , but did not result in higher termination rates than with the Nova-T device . No changes in body weight were recorded for the levonorgestrel-IUDs and a slight decrease in both systolic and diastolic blood pressure was found after one year of use . No infections were recorded First year results of a r and omized study of 1509 users of the Copper T380Ag with a silver core or of an IUD releasing 20 mcg day of levonorgestrel  are reported . The cumulative gross pregnancy rate for each device was 0.3 per 100 at one year , with more than 490 women having one year of use with each device . The levonorgestrel-releasing device was associated with significantly fewer bleeding days and significantly increased hemoglobin levels when compared with pre-admission values or the one year values observed among users of the TCu380Ag . Terminations attributable to amenorrhea were significantly more frequent among users of the levonorgestrel-releasing device . The TCu 380Ag was associated with increased frequency and severity of dysmenorrhea compared with pre-admission levels or with the steroid-releasing device . Hemoglobin levels were somewhat reduced among users of the TCu 380Ag device . Terminations attributable to pain were , however , not significantly different by device . Continuation rates at the end of the first year were not significantly different by device An intrauterine device , releasing approximately 20 micrograms/day of levonorgestrel ( LNg 20 ) , used by 1124 women , was studied in a r and omized trial of five years duration in comparison with the Copper T , model TCu 380Agm  in 1121 women . At five years , the gross cumulative pregnancy rate of 1.1 + /- 0.5 per 100 among users of the LNg 20 devices was not significantly different from the rate of 1.4 + /- 0.4 per 100 experienced by users of the Copper T 380Ag . The steroid-releasing IUD had significantly higher termination rates for expulsion and amenorrhea , a significantly lower termination rate for other menstrual problems and pain , and a lower continuation rate . The five-year continuation rate among women using the TCu 380Ag was 40.6 per 100 as compared with that of 33.0 per 100 among women r and omized to the LNg 20 device ( P less than .001 ) . Terminations attributed to amenorrhea with the LNg device primarily account for differences in continuation . These two intrauterine devices are the most effective long-term , reversible IUDs yet reported in the literature . No other contraceptive methods have exhibited such low long-term pregnancy rates in r and omized comparative trials Life-table methods used for the analysis and interpretation of  contraceptive follow-up studies  differ from those used in other areas of medical research . The historical development of these methods in the contraceptive literature is outlined and the two main methods are discussed , compared and shown to differ mainly in their nomenclature ; their results are very similar in practice . The daily life-table  method is simpler to apply and interpret , and facilitates analysis using the logrank statistic as well as powerful regression modelling techniques for survival data OBJECTIVES To measure and compare the incidence of adverse events during use of two medicated intrauterine devices ( IUDs ) .  DESIGN A multicenter prospect i ve 7-year r and omized study . SETTING Family planning clinics , primarily in developing countries . SUBJECTS Women age 18 to 38 years at admission , desiring contraception and without contraindications to IUDs . MAIN OUTCOME MEASURES Incidence of complaints , conditions , and rates of specific termination for each IUD . METHODS Subjects recorded menstrual events , and clinical staff registered all complaints and conditions found on examination at four first-year clinic visits and at semiannual visits thereafter . Difference in rates were analyzed by chi 2 statistics . RESULTS Annual pregnancy rates for each IUD averaged 0.2/100 women whereas upper genital tract infection occurred at rates of 0.6 to 0.7 per 100 years of use . The levonorgestrel-releasing IUD significantly decreased bleeding and spotting days in comparison with historical data for noncontraceptors and with the copper-medicated IUD .  Dysmenorrhea , vaginitis , and myoma in women with the levonorgestrel IUD were markedly decreased in comparison with the experience of copper IUD users . Significantly higher rates of amenorrhea , delayed ovarian follicular atresia , skin and hair conditions , and headache were observed with the steroid IUD than with the copper-releasing IUD . Rates of reported adverse effects for either IUD were highest in the first 2 years of use and among women under age 25 . CONCLUSIONS Long-term use of copper or levonorgestrel IUDs is characterized by very low rates of pregnancy and by a low and declining annual incidence of side effects , including pelvic infection and borderline anemia . The levonorgestrel-releasing IUD reduced the incidence of bleeding and , in the long term , of myoma and myoma-related surgery in comparison with the copper T IUD . Both IUDs proved highly acceptable and had few unanticipated side effects Following use of either the Levonorgestrel 20 mcg/day or the TCu 380 Ag IUD in a r and omized comparative study , 110 women stopped contracepting to have planned pregnancies .  Pregnancy rates and recovery of fertility have been assessed . Age at acceptance , duration of use , parity and intervals between last pregnancy and IUD insertion or removal were similar for both groups . Life table pregnancy rates at one year were higher than 90 per cent for both device groups ; but because some women quickly changed their minds or had been at risk of pregnancy only a short time before the analysis date , only 60.9 percent had actually become pregnant . Median time to planned pregnancy was 3 months for the TCu 380 Ag group and 4 months for the Levonorgestrel 20 group . Neither duration of use nor age at insertion or age at termination affected the pregnancy rates significantly A r and omised double blind study of a plain T-shaped IUD and an active T-shaped IUD releasing 65 micrograms/day of progesterone , has been completed in four centres . A study of 1320 progester 
    Output:
    
When the LNG-20 IUS was compared to Norplant-2 , the LNG-20 users were significantly more likely to experience amenorrhoea and oligomenorrhoea , but significantly less likely to experience prolonged bleeding and spotting .
REVIEW ERS ' CONCLUSIONS Current evidence suggests LNG-20 IUS users are no more or less likely to have unwanted pregnancies than IUD > 250mm2 and Norplant-2 users .
The LNG-20 IUS was more effective in preventing either intrauterine or extrauterine pregnancies than IUDs < = 250mm2 .
The contraceptive effectiveness of Progestasert was significantly better than non-medicated IUDs , but no difference was observed when compared to IUDs<=250mm2 .
Continuation of LNG-20 IUS use was similar to continuation of the non-hormonal IUDs and Norplant-2 .