***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 
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    Input: OBJECTIVE To assess the effects of the combined contraceptive vaginal ring NuvaRing on ovarian function . DESIGN R and omized , open-label , crossover study . SETTING Clinical pharmacology unit . PARTICIPANT(S ) Sixteen healthy female volunteers . INTERVENTION(S ) Group 1 : one cycle of combined oral contraceptive containing desogestrel ( 150 microg ) and ethinyl estradiol ( 30 microg ) ( desogestrel/EE COC ) , followed by a NuvaRing treatment period . Group 2 : NuvaRing treatment period followed by a cycle of desogestrel/EE COC . MAIN OUTCOME MEASURE(S ) Follicular diameter , serum hormone concentrations ( follicle-stimulating hormone , 17beta estradiol , luteinizing hormone , and progesterone ) , and endometrial thickness . RESULT ( S ) NuvaRing use for the recommended period of 3 weeks result ed in complete inhibition of ovulation , as assessed by vaginal ultrasound ( follicular diameter ) and by serum luteinizing hormone and progesterone concentrations . Inhibition of ovulation was maintained for an additional 2 weeks of NuvaRing use . Ovarian suppression between the groups was comparable . Furthermore , ovarian suppression after 3 weeks of NuvaRing use was comparable to that on day 21 of DGS/EE COC intake . NuvaRing was well tolerated . CONCLUSION ( S ) NuvaRing completely inhibited ovulation throughout the normal 3-week period and the extended period of use . Ovarian suppression was comparable to that with desogestrel/EE COC BACKGROUND NuvaRing is a combined contraceptive vaginal ring design ed for 3 weeks continuous use followed by a 1 week ring-free period . The present study evaluated  ovarian function in women who were instructed to either adhere to , or deviate from , the recommended regimen of use . METHODS In this open-label , r and omized study , 45 women aged between 18 and 35 years used NuvaRing  for one cycle in which the ring was used according to the recommended regimen . Women in group A ( n = 15 ) then continued with a ' normal ' 3 week period of ring use after which the restoration of ovarian function-i.e . the time to ovulation-for each woman was determined by daily vaginal ultrasound and serum hormone levels . For women in group B ( n = 15 ) , the second cycle consisted of only 3 consecutive days of ring use , after which each woman was monitored until ovulation . Women in group C ( n = 15 ) were not permitted to start a second ' normal ' cycle until a follicle with a diameter of 13 mm was observed by vaginal ultrasound ; subsequently , the development of these follicles during the second cycle of ring use was monitored daily . RESULTS Irrespective of the length of the second cycle , 3 weeks ( group A ) versus 3 days ( group B ) , a new cohort of follicles needed to be recruited and the time to ovulation after ring removal was similar ( 19 versus 17 days ) . The median time needed to develop a follicle up to 13 mm in diameter ( group C ) was 11 days ( range 8 - 21 days ) ; none of the women ovulated after insertion of the second ring . CONCLUSION NuvaRing is a highly effective , reversible method of hormonal contraception . Ovulation , at least until the stage of a 13 mm dominant follicle , is prevented and as little as 3 consecutive days of NuvaRing use interferes with follicle growth OBJECTIVE To compare the effects of the contraceptive patch to oral contraceptives ( OCs ) on follicular size and incidence of ovulation in normal cycles and after dosing errors . DESIGN R and omized , open-label . SETTING Twelve centers . PATIENT(S ) One hundred twenty-four ovulatory women . INTERVENTION(S ) Subjects received either the patch ( groups 1 and 2 ) or one of three OCs . Correct dosing occurred in cycles 1 , 2 , 3 , and 5 . The following dosing errors were planned during cycle 4 , a shortened 10-day cycle : [ 1 ] patch group 1 subjects wore one patch for 10 consecutive days ; [ 2 ] for patch group 2 and OC subjects , 7 dosing days were followed by 3 drug-free days . MAIN OUTCOME MEASURE(S ) Follicular size , as determined at each cycle by the maximum mean follicular diameter . RESULT ( S ) After a 3-day dosing error , follicular size was significantly smaller in the patch group ( mean , 7.0 mm ) vs. each OC group ( range of means , 11.8 - 17.1 mm ) . Similar results were seen after proper dosing . The incidence of ovulation was significantly lower for the patch users than for women using OCs  . CONCLUSION ( S ) Follicular size and incidence of ovulation were significantly reduced among  contraceptive patch users compared with women using OCs  in normal cycles and after planned dosing errors Objective The purpose of this study was to determine whether missing pills in an oral contraceptive ( OC ) cycle result ed in folliculogenesis and eventual ovulation . Methods Fifteen women selected from a population requesting tubal reanastomosis were r and omized into three groups and issued pill packs missing four consecutive pills in specific sequences , as follows : group I , days 1–4 ; group II , days 3–6 ; and group III , days 6–9 . Serum was drawn for assay of LH , FSH , estradiol ( E2 ) , and progesterone  , and  serial ovarian ultrasound examinations were done to study follicular development throughout the cycle at 4-day intervals . Results No subject ovulated , as suggested by serum progesterone concentrations ( not exceeding 0.63 ng/mL for any woman ) and ultrasound assessment of follicular development ( no follicular diameter exceeding 13 mm ) . The highest ( mean ± st and ard deviation ) serum concentrations of LH and FSH in any group ( 13.25 ± 18.71 and 14.40 ± 7.71 mIU/mL , respectively ) and of E2 ( 44.35 ± 26.79 pg/mL ) were observed during or immediately after the pill-free interval . Ovarian ultrasound examinations suggested suppressed folliculogenesis in all groups . No functional ovarian cysts were detected . Conclusions Oral contraceptives exerted a similar degree of pituitary and ovarian suppression even when the subjects missed four pills at varying times in a cycle . The anovulatory effect persisted when the OC pills were reinstituted and taken reliably after an interval of noncompliance We evaluated ovarian follicular development  in women during compliant use of oral contraceptives ( OC ) . Thirty-six healthy women received : [ 35 microg ethinyl estradiol (21)/180 microg norgestimate ( 7 ) , 215 microg norgestimate ( 7 ) , 250 microg norgestimate ( 7 ) ] ; [ 30 microg ethinyl estradiol (21)/150 microg desogestrel ( 21 ) ] ; or [ 20 microg ethinyl estradiol (21)/100 microg levonorgestrel ( 21 ) ] for 3 consecutive 28-day cycles . Transvaginal ultrasonography was performed every third day to monitor follicular development . If a follicle reached > or = 14 mm , ultrasonography was performed daily and blood drawn every other day to determine estradiol-17beta concentrations . Seventeen of 36 women ( 47 % ) grew follicles > or = 10 mm . Nine of the 17 women ( 53 % ) grew follicles > or = 14 mm , in association with increased serum concentrations of estradiol-17beta . Thirty-seven of 43 follicles > or = 10 mm ( 86 % ) emerged during the hormone-free interval ( HFI ) . No ovulations were observed . Our results supported the hypothesis that follicular development to an ostensibly ovulatory diameter occurs during compliant OC use , in association with loss of endocrine suppression during the HFI OBJECTIVE To assess the contraceptive efficacy , cycle control , tolerability , and user acceptability of a novel combined contraceptive vaginal ring for up to 13 cycles . METHODS Healthy women requesting contraception were enrolled in this 1‐year multicenter study . Each ring released 120 μg of etonogestrel and 15 μg of ethinylestradiol daily , and was used for 3 weeks followed by a 1‐week ring‐free period . RESULTS A total of 2322 women started treatment and so formed the intent‐to‐treat population . Subjects were followed for 23,298 cycles , equivalent to 1786 woman‐years . Compliance was good with 85.6 % of cycles in full compliance with specified criteria . In the intent‐to‐treat population , 21 pregnancies occurred , giving a Pearl Index of 1.18 ( 95 % confidence interval 0.73 , 1.80 ) . Eleven of the pregnancies were attributable to noncompliance ; the Pearl Index for the per‐ protocol population was 0.77 ( 95 % confidence interval 0.37 , 1.40 ) . The mean incidence of withdrawal bleeding was 98.5 % in all cycles . Irregular bleeding occurred in 5.5 % of all cycles , and in most women , early or late withdrawal bleeding was restricted to spotting . The ring was well tolerated with a low incidence of adverse events ; only 2.5 % of all discontinuations were device related . The ring was easy to insert and remove and did not interfere with intercourse . Eighty‐five percent of women were satisfied with the ring , and 90 % would recommend its use to others . CONCLUSION The ring is an effective contraceptive with excellent cycle control that is convenient , well tolerated , and highly acceptable to users A longitudinal study was conducted to evaluate the ability of a low-dose triphasic oral contraceptive to suppress ovulation as documented by frequent ultrasonographic scanning and progesterone determinations , even in the event of a missed pill . The extent of follicular growth and maturation , the incidence of escape ovulation , and the effect of correct and incorrect pill intake were assessed in 30 evaluable women during two consecutive spontaneous menstrual cycles . After the first cycle , 11 of 30 women ( 36.6 % ) had follicle-like structures of at least 10 mm in diameter . Ten of 11 structures gradually disappeared during the second cycle , with one persistent structure remaining through the second cycle . Seven of 30 women ( 23 % ) developed follicle-like structures during the second cycle . Of these , one woman had a probable ovulation , and another had an elevated progesterone level without follicle rupture , suggesting the luteinized unruptured follicle syndrome . Both of these women missed a pill on day 1 of the second cycle . In all cases cervical scores indicating hostility were noted . Thus , although suppression of ovarian activity may have been incomplete when oral contraceptives were incorrectly taken , secondary mechanisms of contraception remained operant . When they were correctly taken , low-dose triphasic oral contraception consistently prevented ovulation In this open , prospect i ve , phase-I study we closely monitored levels of endogenous progesterone , 17β-estradiol , luteinizing hormone ( LH ) and follicle stimulating hormone in six healthy women . We determined plasma concentrations every 1–3 days during one untreated baseline cycle and during the first treatment cycle with regular pill intake of an oral contraceptive containing 30 μg ethinylestradiol plus 75 μg gestodene . During the following two treatment cycles , two tablets were deliberately omitted ( in cycle 2 on days 6/7 and in cycle 3 on days 11/12 ) . All but possibly one volunteer ovulated in the untreated pre-cycle , as concluded from LH peaks followed by marked increases of progesterone . During the regular first treatment cycle and even after deliberate omission of two tables in treatment cycles 2 and 3 , the progesterone and estradiol levels remained low , so that we concluded that no ovulation took place . However , two volunteers showed some sort of LH peak in the first regular treatment cycle and all women showed LH increases of > 40 μg/ml in at least one omission cycle . In ten out of 12 cycles , omissions of pill intake were followed by an episode of intermenstrual bleeding . In conclusion , we have shown that , after omission of two consecutive oral contraceptive tables , the endogenous hormone parameters did not provide evidence for ovulation . Although this provides confirmation of the robustness of this oral contraceptive towards non-compliance , the widely published practical recommendations should be followed This study was design ed to evaluate follicular activity  in women taking oral contraceptives with imposed imperfect compliance . After completing a 28-day cycle of either triphasic norgestimate/EE ( NGM/EE ) ( Ortho Tri-Cyclen , Ortho-McNeil Pharmaceutical , Raritan , NJ ) or monophasic levonorgestrel/EE ( LNG/EE ) ( Alesse , Wyeth-Ayerst Laboratories , Philadelphia , PA ) , women were instructed to intentionally " miss " the first two active pills of the next pack . The first two tablets in the second treatment cycle were deliberately omitted , thereby extending the pill-free interval from 7 days to 9 days . Subjects were r and omized to take NGM/EE ( n = 40 ) or LNG/EE ( n = 39 ) for two consecutive cycles . The mean maximum follicular diameter was significantly greater in women taking LNG/EE than in those taking N 
    Output:
    
For studies providing indirect evidence on the effects of missed CHCs , it is unclear how differences in surrogate measures correspond to pregnancy risk .
Fewer studies examined the transdermal patch and vaginal ring than combined oral contraceptives