***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: In a parallel , multicenter study in Norway and Finl and involving a total of 196 healthy women ( mean age 22.4 years , range 18–30 ) , the effects on serum lipids and lipoproteins of two multiphasic oral contraceptives containing ethinyl estradiol ( EE ) but different progestins were examined . One formulation contained EE 35 μg and norethisterone ( NET ) 0.5 mg on days 1–7 and days 17–21 and elevated NET 1.0 mg during the midphase ( days 8–16 ) . The other formulation contained EE 30 μg on days 1–6 and days 12–21 and 40 μg on days 7–11 and phased levonorgestrel ( LGN ) : 50 μg ( days 1–6 ) , 75 μg ( days 7–11 ) and 125 μg ( days 12–21 ) . Both formulations induced significant elevation of total cholesterol ( 6.7 and 4.1 % ) , Apo B ( 8.1 and 7.0 % ) as well as HDL ( 6.4 and 3.7 % ) for the EE/NET and EE/LGN formulation respectively . Mean serum levels of triglycerides were significantly elevated ( 58 and 47 % ) . However , all mean serum lipid and lipoprotein values remained within the normal range , and no change in the calculated cholesterol ratio ( HDL/total cholesterol ) nor lipoprotein ratio ( HDL/(HDL+LDL ) ) was observed . No significant difference between the formulations could be detected with respect to the effect on serum lipids and lipoproteins measured . The change in total cholesterol was smaller than reported in many studies of monophasic preparations . Taken together , these data suggest that only small alterations in lipid metabolism are elicited by these oral contraceptives PURPOSE This open-label , r and omized study evaluated the effect of two different oral contraceptives on body weight and composition during one cycle of treatment . METHOD Eighty women ( mean age , 24.6 years ) were r and omized into three groups and given one of the following contraceptive methods : ethinylestradiol 15 mug/gestodene 60 mug ( EE/GST , n=25 ) , ethinylestradiol 30 mug/drospirenone 3 mg ( EE/DRS , n=29 ) or male condom ( control group , n=26 ) . Bioelectric impedance analysis ( BIA ) was carried out on the first , 10th and 21st days during the use of oral contraceptives or in the menstrual cycle ( control group ) , and total body water ( TBW ) , fat mass ( FM ) and fat-free mass ( FFM ) were measured . RESULTS No significant variations in TBW , FM or FFM were observed in the three groups during the cycle . Intergroup analysis showed no differences in TBW or FM ; however , users of EE/GST showed a statistically significant increase in FFM compared to the control group . CONCLUSION The different doses of ethinylestradiol associated with gestodene or drospirenone showed no statistically significant effects on TBW or FM during one cycle of observation In an open , r and omized study in an outpatient clinic of a large teaching hospital , thirty-one female volunteers with regular cycles and established ovulation by ultrasonography were given one of two triphasic oral contraceptives containing ethinylestradiol combined with levonorgestrel or desogestrel during six cycles of treatment . The main outcome measures were transvaginal ultrasonography and serum E2 and P measurements in pill cycles 1 , 3 and 6 . No ovarian activity was found in 10 subjects . Among the remaining 21 women who showed ovarian activity , most follicle-like structures developed in the pill-free week and decreased in size or disappeared in the first pill week . One women taking triphasic desogestrel had evidence of a luteinized unruptured follicle and one women taking triphasic levonorgestrel had a possible ovulation . The latter women also showed symptoms of lower abdominal pain . A statistically significant difference in ovarian activity between the two oral contraceptives could not be established . The two triphasic oral contraceptives suppressed ovarian activity to the same degree . A trend was seen towards increasing ovarian activity with duration of use in both treatment groups 398 new users of oral contraceptives at the Research Clinic of the Southwest Foundation Texas were asked if they experienced nausea vomiting headache or breast discomfort nervousness or depression and had weight and blood pressure recorded in the pretreatment cycle and at monthly visits . Each received placebo Oracon ( sequential ) Ovulen-21 ( combination ) Norinyl-1 or .5 mg chlormadinone acetate in a double-blind protocol incorporating a pretreatment placebo cycle crossover to an active pill for 4 cycles and 2 more crossovers for Cyles 5 and 6 . The only symptoms significantly higher than in the pretreatment ( placebo ) cycle were nausea and vomiting with Oracon ( p greater than .05 ) and headache with Ovulen ( p greater than .05 ) . Pointing out that the highest incidence of complaints occurred in the placebo cycle the authors conclude that controls are necessary in contraceptive trials but the first cycle is not valid for comparison A phase III clinical study was carried out among 5680 fertile Chinese women to evaluate efficacy and side effects of three monthly  injectable contraceptives : Mesigyna , Cyclofem and Chinese Injectable No. 1 . When used in a once-a-month treatment schedule ( part 1 of study ) , the effectiveness of Chinese Injectable No. 1 was unacceptably low ; 36 pregnancies occurred during the first 1743 women-months of use , 16 before the second injection . The study was restarted with a revised injection schedule for Injectable No. 1 : two injections separated by 9 + /- 1 days during the first month and subsequent injections given 10 - 12 days after the onset of bleeding , or if no bleeding occurred , 28 days after previous injection . In part 2 of the study , 988 , 990 and 992 subjects were provided Mesigyna , Cyclofem and Injectable No. 1 , respectively . Life-table pregnancy rates at one year were 0.41 % , 0 % and 0.77 % ( p < 0.05 ) , respectively ; the overall discontinuation rates at one year were 13.9 % , 19.1 % and 20.4 % ( p < 0.001 ) . Discontinuation rates for bleeding problems were significantly different between the groups : discontinuation rates for amenorrhea were 0.58 % , 3.71 % and 0.68 % ( p < 0.001 ) for Mesigyna , Cyclofem and Injectable No. 1 ; for other bleeding problems , the rates were 4.88 % , 8.38 % and 12.64 % ( p < 0.001 ) . There were no significant differences between the groups regarding discontinuation for other medical or non-medical reasons . Mean weight changes after one year of use were small : 0.73 , 0.86 and 0.17 kg for the three groups , respectively . Both Mesigyna and Cyclofem were very effective for contraception , but Mesigyna appeared to be tolerated slightly better with regard to cycle control ; the modified dose regimen for Injectable No. 1 also gave a low pregnancy rate but was associated with higher rates of discontinuation OBJECTIVE : To compare bleeding profiles and satisfaction among women using a norelgestromin/ethinyl estradiol ( E2 ) transdermal contraceptive patch in an extended regimen to those among women using a traditional 28-day patch regimen . METHODS : Healthy , regularly menstruating women ( N = 239 ) were r and omly assigned ( 2:1 ratio ) to receive the norelgestromin/ethinyl E2 transdermal patch in an extended regimen ( weekly application for 12 consecutive weeks , 1 patch-free week , and 3 more consecutive weekly applications , n = 158 ) or a cyclic regimen ( 4 consecutive cycles of 3 weekly applications and 1 patch-free week , n = 81 ) . Subjects recorded bleeding data daily and completed satisfaction question naires . Subjects and investigators provided overall assessment s of the regimens . RESULTS : Extended use of the norelgestromin/ethinyl E2 transdermal patch result ed in fewer median bleeding days ( 6 compared with 14 , P < .001 ) , bleeding episodes ( 1 compared with 3 , P < .001 ) , and bleeding or spotting episodes ( 2 compared with 3 , P < .001 ) compared with cyclic use during days 1–84 ; median numbers of bleeding or spotting days were similar between regimens ( 14 compared with 16 , P = .407 ) during this time . Extended use delayed median time to first bleeding to 54 days compared with 25 days with cyclic ( P < .001 ) . Subjects were highly satisfied with both regimens . Although not statistically significant , slightly more adverse events were reported with the extended than with the 28-day regimen . CONCLUSION : Compared with cyclic use , extended use of the norelgestromin/ethinyl E2 transdermal patch delayed menses and result ed in fewer bleeding days . This regimen may represent a useful alternative for women who prefer fewer episodes of withdrawal bleeding . LEVEL OF EVIDENCE : PURPOSE To determine the effect of oral contraceptives ( OC ) on bone mass and stress fracture incidence in young female distance runners . METHODS One hundred fifty competitive female runners ages 18 - 26 yr were r and omly assigned to OC ( 30 microg of ethinyl estradiol and 0.3 mg of norgestrel ) or control ( no intervention ) for 2 yr . Bone mineral density ( BMD ) and content ( BMC ) were measured yearly by dual x-ray absorptiometry . Stress fractures were confirmed by x-ray , magnetic resonance imaging , or bone scan . RESULTS R and omization to OC was unrelated to changes in BMD or BMC in oligo/amenorrheic ( N=50 ) or eumenorrheic runners ( N=100 ) . However , treatment-received analyses ( which considered actual OC use ) showed that oligo/amenorrheic runners who used OC gained about 1 % per year in spine BMD ( P<0.005 ) and whole-body BMC ( P<0.005 ) , amounts similar to those for runners who regained periods spontaneously and significantly greater than those for runners who remained oligo/amenorrheic ( P<0.05 ) . Dietary calcium intake and weight gain independently predicted bone mass gains in oligo/amenorrheic runners . R and omization to OC was not significantly related to stress fracture incidence , but the direction of the effect was protective in both menstrual groups ( hazard ratio [ 95 % CI ] : 0.57 [ 0.18 , 1.83 ] ) , and the effect became stronger in treatment-received analyses . The trial 's statistical power was reduced by higher-than-anticipated noncompliance . CONCLUSION OC may reduce the risk for stress fractures in female runners , but our data are inconclusive . Oligo/amenorrheic athletes with low bone mass should be advised to increase dietary calcium and take steps to resume normal menses , including weight gain ; they may benefit from OC , but the evidence is inconclusive This open-label r and omized study compared the effects of two combined oral contraceptives ( OCs ) containing 3 mg drospirenone (DRSP)/30 microg ethinyl estradiol ( EE ) with 150 microg levonorgestrel (LNG)/30 microg EE on the prevalence and changes from baseline of premenstrual symptoms after six cycles . The symptoms were measured using the Women 's Health Assessment Question naire .  Subjects receiving DRSP/EE  had fewer prevalence of premenstrual symptoms than those receiving LNG/EE after six cycles . A significantly lower score of negative affect category in the premenstrual phase was demonstrated in those receiving DRSP/EE more than LNG/EE . The DRSP/EE group showed a greater improvement of mean scores from baseline in the premenstrual phase compared with those who received LNG/EE on negative affect as seen in the items on anxiety , irritability , feeling sad or blue and weight gain in the category of water retention . In conclusion , OCs containing DRSP have beneficial effects in reducing the prevalence of premenstrual symptoms especially the symptoms of negative affect and weight gain , particularly when compared to LNG/EE . Hence , it should be recommended for women who are susceptible to these adverse symptoms The efficacy and acceptability of two third generation oral contraceptives in Thai women were evaluated in a prospect i ve , open , group-comparative , r and omized , multicenter trial of women asking for contraception . In six Family Planning Centers and Outpatient Gynaecological Clinics in urban areas in Thail and , 783 healthy women who were at risk for pregnancy and did not have contraindications to oral contraceptive use were r and omly allocated to one of the two study groups . An oral contraceptive containing 30 mcg ethinylestradiol and 150 mcg desogestrel was given to 394 women and an oral contraceptive with the same amount of ethinylestradiol and 75 mcg gestodene to 389 women during 6 cycles . Criteria of cycle control , side effects and the presence and severity of acne vulgaris were assessed and blood pressure and body weight measured at pretreatment and after cycles 1 , 
    Output:
    
MAIN RESULTS The three placebo-controlled , r and omized trials did not find evidence supporting a causal association between combination oral contraceptives or a combination skin patch and weight gain .
Most comparisons of different combination contraceptives showed no substantial difference in weight .
In addition , discontinuation of combination contraceptives because of weight gain did not differ between groups where this was studied .
Available evidence was insufficient to determine the effect of  combination contraceptives on weight , but no large effect was evident