***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: BACKGROUND Prediction models for spontaneous pregnancy  may be useful tools to select subfertile couples that have good fertility prospect s and should therefore be counselled for expectant management . We assessed the accuracy of a recently published prediction model for  spontaneous pregnancy  in a large prospect i ve validation study . METHODS In 38 centres , we studied a consecutive cohort of subfertile couples , referred for an infertility work-up . Patients had a regular menstrual cycle , patent tubes and a total motile sperm count ( TMC ) > 3 x 10(6 ) . After the infertility work-up had been completed , we used a prediction model to calculate the chance of a spontaneous ongoing pregnancy ( www.freya.nl/probability.php ) . The primary end-point was time until the occurrence of a spontaneous ongoing pregnancy within 1 year . The performance of the pregnancy prediction model was assessed with calibration , which is the comparison of predicted and observed ongoing pregnancy rates for groups of patients and discrimination . RESULTS We included 3021 couples of whom 543 ( 18 % ) had a spontaneous ongoing pregnancy , 57 ( 2 % ) a non-successful pregnancy , 1316 ( 44 % ) started treatment , 825 ( 27 % ) neither started treatment nor became  pregnant  and 280 ( 9 % ) were lost to follow-up . Calibration of the prediction model was almost perfect . In the 977 couples ( 32 % ) with a calculated probability between 30 and 40 % , the observed cumulative pregnancy rate at 12 months was 30 % , and in 611 couples ( 20 % ) with a probability of > or=40 % , this was 46 % . The discriminative capacity was similar to the one in which the model was developed ( c-statistic 0.59 ) . CONCLUSIONS As the chance of a spontaneous ongoing pregnancy among subfertile couples can be accurately calculated , this prediction model can be used as an essential tool for clinical decision-making and in counselling patients . The use of the prediction model may help to prevent unnecessary treatment OBJECTIVE To assess whether pregnancy history can predict the occurrence of a spontaneous ongoing pregnancy in subfertile couples . DESIGN Prospect i ve cohort study . SETTING Thirty fertility centers in the Netherl and s. PATIENT(S ) Subfertile , ovulatory women with at least one patent tube and male partners without severely impaired semen quality . INTERVENTION(S ) Fertility work-up , including a detailed pregnancy history . MAIN OUTCOME MEASURE(S ) Spontaneous ongoing pregnancy . RESULT ( S ) We included 4445 couples , of whom 793 ( 18 % ) had a spontaneous ongoing pregnancy  within 1 year of follow-up . Previous live birth and miscarriage in current partnership were both associated with higher fecundity as compared with primary infertility ( hazard rate ratios for spontaneous pregnancy [ HR ] 1.4 ; 95 % CI , 1.2 - 1.7 and 1.3 ; 95 % CI , 1.0 - 1.5 , respectively ) . Pregnancies in a woman 's previous partnerships did not affect the fecundity of the couple . A pregnancy in a previous partnership of the male partner was associated with lower fecundity ( HR 0.76 ; 95 % CI , 0.58 - 0.99 ) . A previous pregnancy after fertility treatment also was associated with lower fecundity ( HR 0.52 ; 95 % CI , 0.30 - 0.90 ) . CONCLUSION ( S ) Accurate prediction of the future fertility of a couple requires an exact assessment of the fertility history of both partners Background The study meant to define the prognostic factors that help in prescribing intrauterine insemination ( IUI ) for infertility treatment which remains an area of continuous improvements . Methods The diagnostic indications of a cohort of  IUI-treated patients and their corresponding  pregnancy rates ( PRs ) were r and omly and prospect ively studied among Saudi cohort of 303 patients for a period of 20 months . The indications of IUI cases were statistically analyzed for those eligible patients over a period of twenty months ( January 2010 till August 2011 ) , and the PR that corresponded to each group was investigated as well . P-value less than 0.05 was considered significant . Results The highest PR , 18.87 % , of the polycystic ovarian syndrome (PCOS)-only diagnosed patients , was significantly higher than the average PR of all other indications combined , 7.22 % , ( p = 0.011 , compared to all other groups combined ) . The second highest PR , 14.0 % , of the tubal factor (TF)-only indication , was double the PR average of all other indications combined , though it did not reach significance . However , PCOS and TF accompanied by other indications caused the PR to drop to 5.88 % and 5.56 % , respectively . However , a group of some hormonal-imbalance based indications had the least PR ( 0.0 % to 2.70 % ) . Those indications were elevated serum FSH , hyperprolactinemia , hypogonadotrophy , hypothyroidism and endometriosis . The rest of the indications had an average PR ( 8.33 % to 11.11 % ) . Conclusion There is a reasonable chance of conception after IUI treatment for female factor infertility except in cases with sever hormonal imbalance . The PCOS cases having the best success chances Multiple factors influence the outcome of  in vitro fertilization and embryo transfer ( IVF-ET ) .  This prospect i ve study was design ed to assess their relative importance , in order to improve prognostic ability and treatment success . Prior to  IVF-ET  , couples were divided into " good " ( GP ) and " poor " ( PP ) prognosis groups according to female age , semen quality , previous response to stimulation , and embryo quality . The data obtained from 716 consecutive treatment cycles then were evaluated using univariate statistics and logistic regression , a technique design ed to assess the relative contribution of significant factors . The pregnancy rate per GP cycle was 14.7 % , compared with 5.4 % per PP cycle ( chi 1(2 ) = 12.7 , P less than 0.001 ) . The most important prognostic factors were female age , the pregnancy rate showing a linear decline after the age of 25 , and previous  failed fertilization  due to abnormal  sperm . The rate of pregnancy also declined after 14 or more follicles were aspirated and /or nine oocytes were retrieved . A formula for the probability of pregnancy , derived from the logistic regression , provides patients with a more accurate prognosis before treatment In this study , we compare the prognostic significance of hysterosalpingography ( HSG ) and laparoscopy for fertility outcome . In a prospect i ve cohort study in 11 clinics participating in the Canadian Infertility Treatment Evaluation Study ( CITES ) , consecutive couples who registered between 1 April 1984 and 31 March 1987 for the evaluation of subfertility and who underwent HSG and laparoscopy were included . Unilateral and bilateral tubal occlusion at HSG and laparoscopy were related to treatment-independent pregnancy . Cox regression was used to calculate fecundity rate ratios ( FRR ) . Of the 794 patients who were included , 114 ( 14 % ) showed one-sided tubal occlusion and 194 ( 24 % ) showed two-sided tubal occlusion on HSG . At laparoscopy , 94 ( 12 % ) showed one-sided tubal occlusion and 96 ( 12 % ) showed two-sided tubal occlusion . Occlusion detected on HSG and laparoscopy showed a moderate agreement beyond chance ( weighted kappa-statistic 0.42 ) . The adjusted FRR of one-sided tubal occlusion at HSG was 0.80 , whereas two-sided tubal occlusion showed an FRR of 0.49 . For laparoscopy , the FRR were 0.51 and 0.15 respectively . After a normal or one-sided occluded HSG , laparoscopy showed two-sided occlusion in 5 % of the patients , and fertility prospect s in these patients were virtually zero . If two-sided tubal occlusion was detected on HSG but not during laparoscopy , fertility prospect s were slightly impaired . Fertility prospect s after a two-sided occluded HSG were strongly impaired in cases where laparoscopy showed one-sided and two-sided occlusion , with FRR of 0.38 and 0.19 respectively . Although laparoscopy performed better than HSG as a predictor of future fertility , it should not be considered as the perfect test in the diagnosis of tubal pathology . For clinical practice , laparoscopy can be delayed after normal HSG for at least 10 months , since the probability that laparoscopy will show tubal occlusion after a normal HSG is very low OBJECTIVE To assess the accuracy of our recently developed prediction model in a prospect i ve validation study to predict the outcome of  intrauterine insemination ( IUI ) .  DESIGN Descriptive prospect i ve validation study . SETTING Seven fertility centers in the Netherl and s. PATIENT(S ) Couples treated with IUI of whom the female partner had a regular cycle . INTERVENTION(S )  Intrauterine insemination with or without controlled ovarian hyperstimulation .  MAIN OUTCOME MEASURE(S ) Ongoing pregnancy after intrauterine insemination . Performance of the prediction model was assessed with calibration and discriminative capacity . Calibration was assessed by comparing the predicted ongoing pregnancy rate with the observed ongoing pregnancy rate . Discriminative capacity was assessed with receiver operation characteristic ( ROC ) analysis . For daily practice , a score worksheet of the vali date d model was developed to estimate the chance of an ongoing pregnancy after IUI per treatment cycle . RESULT ( S ) We included 1,079 subfertile couples who underwent 4,244 cycles of IUI .  There were 278 ongoing pregnancies  , that is , an ongoing pregnancy rate of 6.6 % per cycle . External validation of the model showed good calibration . The predicted probability never differed by more than 1.5 % of the mean observed probability . The area under the ROC curve was 0.56 ( 95 % confidence interval , 0.53 - 0.59 ) at external validation . CONCLUSION ( S ) The prediction model was able to make a good distinction between couples with a good pregnancy chance and those with a poor pregnancy chance after IUI . This model can help in deciding which couples will benefit from IUI and which couples will not OBJECTIVE To evaluate the cumulative singleton live birth rate after classic ovulation induction in women with anovulatory polycystic ovary syndrome and to vali date a previously developed prediction model . DESIGN Prospect i ve follow-up study . SETTING Tertiary infertility unit . PATIENT(S ) Validation cohort of 108 treatment-naïve anovulatory PCOS patients . INTERVENTION(S ) Conventional ovulation induction , applying clomiphene citrate as first-line treatment , followed by exogenous gonadotropins as second-line intervention . MAIN OUTCOME MEASURE(S ) Singleton live birth prediction . Model calibration and discrimination were assessed for the initial model ( variables included age , duration of infertility , and insulin/glucose ratio ) and a second model in which the insulin/glucose ratio was replaced by body mass index . RESULT ( S ) The cumulative singleton live birth rate after 12 and 24 months was 60 % and 78 % , respectively . Overall , the observed rates were higher than predicted : hazard ratio 1.21 ( 95 % confidence interval [ CI ] 0.89 , 1.64 ) , first model and 1.25 ( 95 % CI 1.20 , 1.30 ) , second model . However , the predictive capacity of the model variables was reliable , with calibration slopes of 0.79 ( 95 % CI -0.04 , 1.63 ) and 1.06 ( 95 % CI 0.95 , 1.18 ) , respectively . CONCLUSION ( S ) The present study confirms the previously reported good treatment prognosis for women with PCOS undergoing classic ovulation induction . Women with a poor prognosis , for whom alternative treatment options may be considered , can best be identified by a prediction model including age , duration of infertility , and body mass index . CLINICAL TRIAL REGISTRATION NUMBER NCT00821379 STUDY QUESTION Can mixture survival models help distinguish infertility from  subfertility in couples with an unexplained unfulfilled child wish ? SUMMARY ANSWER Mixture models estimated that 47 % of the couples were infertile ; female age and previous pregnancy were significantly related to infertility , whereas duration of child wish was associated with a longer time to pregnancy for subfertile couples . WHAT IS KNOWN ALREADY To differentiate between couples who require assisted conception and couples who still have good chances of natural , i.e. unassisted , conception , several prediction models of natural conception have been developed . Prognostic factors in these models are usually assessed by Cox proportional hazard models that can not differentiate between couples with an unfulfilled child wish who are subfertile , i.e. have reduced ability to conceive naturally , and couples who are really infertile , i.e. are completely unable to conceive naturally . We evaluated whether a mixture survival model can make such a distinction . STUD 
    Output:
    
CONCLUSION Prediction model can be clinical ly applied if the model can be statistically evaluated and has a good validation for treatment success .