***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: Clinical trials , systematic review s and guidelines compare beneficial and non-beneficial outcomes following interventions . Often , however , various studies on a particular topic do not address the same outcomes , making it difficult to draw clinical ly useful conclusions when a group of studies is looked at as a whole.1 This problem was recently thrown into sharp focus by a systematic review of interventions for preterm birth prevention , which found that among 103 r and omised trials , no fewer than 72 different outcomes were reported.2 There is a growing recognition among clinical research ers that this variability undermines consistent synthesis of the evidence , and that what is needed is an agreed st and ardised collection of outcomes – a “ core outcomes set ” – for all trials in a specific clinical area.1 Recognising that the current inconsistency is a serious hindrance to progress in our specialty , the editors of over 50 journals related to women 's health have come together to support The CROWN ( CoRe Outcomes in WomeN 's health ) Initiative ( Box 1 ) . ! [Graphic][1 ] Box 1 # # # Aims of The CROWN Initiative ( http://www.crown-initiative.org ) 1 . Form a consortium among all gynaecology-obstetrics and related journals to promote core outcome sets in all areas of our specialty . … [ 1 ] : OBJECTIVES : To compare the efficacy of letrozole and clomiphene citrate ( CC ) in patients of anovulatory polycystic ovarian syndrome ( PCOS ) with infertility . MATERIAL S AND METHODS : This prospect i ve r and omized clinical trial included 204 patients of PCOS . 98 patients ( 294 cycles ) received 2.5–5 mg of letrozole ; 106 patients ( 318 cycles ) received 50–100 mg of CC ( both orally from Days 3–7 of menstrual cycle ) . The treatment continued for three cycles in both the groups . Main outcome measures : ovulation rate , endometrial thickness , and pregnancy rate . Statistical analysis was done using SPSS 13 software . P value less than 0.05 was considered significant . RESULTS : The mean number of dominant follicles in letrozole groups and CC groups was 1.86±0.26 and 1.92±0.17 , respectively ( P=0.126 ) . Number of ovulatory cycle  in letrozole group was 196 ( 66.6 % ) versus 216 ( 67.9 % ) in CC group ( P=0.712 ) . The mean mid-cycle endometrial thickness was 9.1±0.3 mm in letrozole group and 6.3±1.1 in CC group , which was statistically significant ( P=0.014 ) . The mean Estradiol [ E2 ] level  in clomiphene citrate group was significantly higher in CC group ( 364.2±71.4 pg/mL ) than letrozole group ( 248.2± 42.2 pg/mL ) . 43 patients from the letrozole group ( 43.8 % ) and 28 patients from the CC group ( 26.4 % ) became pregnant . CONCLUSION : Letrozole and CC have comparable ovulation rate . The effect of letrozole showed a better endometrial response and pregnancy rate compared with CC BACKGROUND An RCT among newly diagnosed , therapy naive women with polycystic ovary syndrome ( PCOS ) showed no significant differences in ovulation rate , ongoing pregnancy rate or spontaneous abortion rate in favour of clomifene citrate plus metformin compared with clomifene citrate . We wanted to assess whether there are specific subgroups of women with PCOS in whom clomifene citrate plus metformin leads to higher pregnancy rates . METHODS Subgroup analysis based on clinical and biochemical parameters of 111 women r and omized to clomifene citrate plus metformin compared with 114 women r and omized to clomifene citrate plus placebo .  The data for age , BMI , waist – hip ratio ( WHR ) and plasma testosterone were available in all women , 2 h glucose in 80 % of women and homeostatic model assessment for assessing insulin sensitivity ( HOMA ) in 50 % of women . RESULTS Of the women who were allocated to the metformin group , 44 women ( 40 % ) reached an ongoing pregnancy . In the placebo group , 52 women ( 46 % ) reached an ongoing pregnancy . There was a significantly different chance of an ongoing pregnancy  for metformin versus placebo between subgroups based on age and WHR ( P = 0.014 ) . There was a positive effect of metformin versus placebo  on pregnancy rate in older women ( ≥28 years ) with a high WHR , a negative effect of metformin versus placebo in young women ( < 28 years ) regardless of their WHR and no effect in older , not viscerally obese women . No significant differences in effect of treatment were found for groups based on BMI , 2 h glucose , HOMA or plasma testosterone . CONCLUSIONS Metformin may be an effective addition to clomifene citrate in infertile women with PCOS , especially in older and viscerally obese patients OBJECTIVE : To compare Letrozole ( 5 mg ) and clomiphene citrate ( 100 mg ) as first line ovulation induction drug in infertile PCOS women . STUDY DESIGN : Prospect i ve R and omised trial . SETTING : A Tertiary level infertility centre . Patients : 103 infertile PCOS women INTERVENTION(S ) : Treatment naïve infertile PCOS women were r and omised to treatment with 5 mg letrozole ( 51 patients ) or 100 mg clomiphene citrate ( 52 patients ) daily starting day 2 to day 6 of menstrual cycle . Timed intercourse or Intra Uterine Insemination ( IUI )  was advised 24 to 36 hours after Human Chorionic Gonadotropin ( HCG ) injection . MAIN OUTCOME MEASURES : Ovulation rate , mono or multi follicular rate , days to ovulation , endometrial thickness , serum progesterone , serum estrogen , pregnancy rate , miscarriage rate . RESULTS : The mean age , Body Mass Index ( BMI ) , duration of infertility in both Clomiphene Citrate ( CC ) and Letrozole groups were similar . Ovulation rate was 73.08 % in letrozole group and 60.78 % in CC , which was not statistically significant ( P=0.398 ) . There was no statistically significant difference between Endometrial thickness ( CC 7.61 ±1.96 , Let 7.65 ± 2.10 ) , Sr E2 on day of HCG ( CC 178.3 ± 94.15 , Let 162.09 ± 73.24 ) , Days to ovulation ( CC 14.2 ± 3.41 ; Let 13.13 ± 2.99 ) and Sr P4 on D21 ( CC 10.58 ± 6.65 ; Let 11.86 ± 6.51 ) . Monofolliculo genesis ( CC 54.84 , Let 79.49 % , P=0.027 ) and Pregnancy rate ( CC 7.84 % , Let 21.56 % P=0.0125 ) were statistically significantly higher in letrozole group . CONCLUSION : Our study shows that letrozole has excellent pregnancy rates compared to clomiphene citrate . Letrozole should be considered at par with clomiphene citrate as first line drug for ovulation induction in infertile PCOS women OBJECTIVE To report the baseline characteristics and racial differences in the polycystic ovary syndrome ( PCOS ) phenotype from a large multicenter clinical trial ( PPCOS ) . DESIGN Double-blind , r and omized trial of three treatment regimens ( with extended release metformin or clomiphene citrate ) . SETTING Academic medical centers . PATIENT(S ) Six hundred twenty-six infertile women with PCOS , aged 18 - 39 years , with elevated T levels and oligomenorrhea ( exclusion of secondary causes ) , seeking pregnancy , with > or = 1 patent fallopian tube , normal uterine cavity , and a partner with sperm concentration > or = 20 x 10(6)/mL in > or = 1 ejaculate . INTERVENTION(S ) Baseline characterization . MAIN OUTCOME MEASURE(S ) Historical , biometric , and biochemical measures of PCOS . RESULT ( S ) There were no significant differences in baseline variables between treatment groups . The overall mean ( + /-SD ) age of the subjects was 28.1 + /- 4.0 years , and the mean body mass index was 35.2 kg/m2 ( + /-8.7 ) .  Polycystic ovaries ( PCOs ) were present in 90.3 % of the subjects , and the mean volume of each ovary was 10 cm3 or more . Of the subjects , 7 % had ovaries that were discordant for PCO morphology . At baseline , 18.3 % of the subjects had an abnormal fasting glucose level ( > 100 mg/dL ) . Asians tended to have a milder phenotype , and whites and African Americans were similar in these measures . CONCLUSION ( S ) The treatment groups were well matched for baseline parameters , and we have added further information to the PCOS phenotype OBJECTIVE Small intervention studies suggest that modest weight loss increases the chance of conception and may improve perinatal outcome , but large r and omized controlled trials ( RCT ) are lacking . Our objective was to investigate the effects of a lifestyle intervention in obese infertile women in a multicenter RCT . DESIGN We r and omly assigned infertile women with body mass index ≥ 29 k/m² to a six-month lifestyle intervention preceding infertility treatment or to prompt infertility treatment . The primary outcome was the vaginal birth of a healthy singleton at term within 2 years of r and omization . RESULTS Between June 2009-June 2102 we r and omly allocated 577 women to one of two treatment strategies : 290 to lifestyle intervention preceding infertility treatment ( intervention group ) and 287 to prompt infertility treatment ( control group ) . Three women withdrew informed consent , leaving 289 and 285 women for analysis . Discontinuation rate during the lifestyle intervention was 22 % . Mean weight loss in the intervention group was 4.4 kg and in the control group 1.1 kg ( p < 0.001 ) ; the primary outcome occurred in 76 women ( 27 % ) in the intervention group versus 100 ( 35 % ) in the control group ( RR : 0.77 , 95 % CI 0.60 to 0.99 ) . The number of natural conceptions leading to ongoing pregnancies was 73 ( 26 % ) versus 46 ( 16 % ) ( RR : 1.6 , 95 % CI 1.2 to 2.2 ) . Maternal pregnancy-related and labor-related complications and neonatal complications were comparable . CONCLUSION In obese infertile women lifestyle intervention preceding infertility treatment did not result in better rates of vaginal birth of healthy singletons at term as compared to prompt infertility treatment BACKGROUND The st and ard therapy for women with unexplained infertility is gonadotropin or clomiphene citrate . Ovarian stimulation with letrozole has been proposed to reduce multiple gestations while maintaining live birth rates . METHODS We enrolled couples with unexplained infertility in a multicenter , r and omized trial . Ovulatory women 18 to 40 years of age with at least one patent fallopian tube were r and omly assigned to ovarian stimulation ( up to four cycles ) with gonadotropin ( 301 women ) , clomiphene ( 300 ) , or letrozole ( 299 ) . The primary outcome was the rate of multiple gestations among women with clinical pregnancies . RESULTS After treatment with gonadotropin , clomiphene , or letrozole , clinical pregnancies occurred in 35.5 % , 28.3 % , and 22.4 % of cycles , and live birth in 32.2 % , 23.3 % , and 18.7 % , respectively ; pregnancy rates with letrozole were significantly lower than the rates with st and ard therapy ( gonadotropin or clomiphene ) ( P=0.003 ) or gonadotropin alone ( P<0.001 ) but not with clomiphene alone ( P=0.10 ) . Among ongoing pregnancies with fetal heart activity , the multiple gestation rate with letrozole ( 9 of 67 pregnancies , 13 % ) did not differ significantly from the rate with gonadotropin or clomiphene ( 42 of 192 , 22 % ; P=0.15 ) or clomiphene alone ( 8 of 85 , 9 % ; P=0.44 ) but was lower than the rate with gonadotropin alone ( 34 of 107 , 32 % ; P=0.006 ) . All multiple gestations in the clomiphene and letrozole groups were twins , whereas gonadotropin treatment result ed in 24 twin and 10 triplet gestations . There were no significant differences among groups in the frequencies of congenital anomalies or major fetal and neonatal complications . CONCLUSIONS 
    Output:
    
Conclusions In women with WHO group II anovulation , letrozole and the combination of clomiphene and metformin are superior to clomiphene alone in terms of ovulation and pregnancy .
Compared with clomiphene alone , letrozole is the only treatment showing a significantly higher rate of live birth .