title: Measuring outcomes in fertility trials: can we rely on clinical pregnancy rates?
abstract: OBJECTIVE
  To assess whether the estimates of treatment effect in randomized clinical trials (RCTs) in reproductive medicine differ when either clinical pregnancy or live birth is used as the outcome measure.
  
  
  METHODS
  Metaanalysis.
  
  
  METHODS
  We analyzed RCTs in reproductive medicine found in systematic reviews published in the Cochrane Library that reported on both clinical pregnancy and live birth.
  
  
  METHODS
  Subfertile couples.
  
  
  METHODS
  For each individual RCT, data on clinical pregnancy and live birth were extracted.
  
  
  METHODS
  We compared the outcome of each study by calculating a kappa-statistic (statistically significant treatment effective or not) and by comparing the odds ratio by calculating the ratio of the odds ratios (ROR).
  
  
  RESULTS
  We found 67 systematic reviews, of which 42 reported on pregnancy and live birth. These 42 reviews included 654 RCTs, of which 143 (22%) reported both on pregnancy and live birth. The pregnancy loss rates in the treatment and control groups were comparable. Of the 143 RCTs, the conclusion based on pregnancy rate and live birth rate was comparable (kappa value of 0.81; 95% confidence interval [CI], 0.68-0.94). The odds ratios estimating treatment effect from pregnancy and live birth were also comparable (ROR, 1.01, 95% CI 0.9 to 1.12).
  
  
  CONCLUSIONS
  Only a minority of randomized clinical trials in reproductive medicine report on live birth. Conclusions on the effectiveness of a treatment based on either clinical pregnancy or live birth as endpoints are comparable.
authors.affiliation: Department of Obstetrics and Gynaecology and National Women's Health, University of Auckland, Auckland, New Zealand.
authors.forename: Jane F
authors.initials: JF
authors.lastname: Clarke
authors.forename: Minouche M E
authors.initials: MM
authors.lastname: van Rumste
authors.forename: Cindy M
authors.initials: CM
authors.lastname: Farquhar
authors.forename: Neil P
authors.initials: NP
authors.lastname: Johnson
authors.forename: Ben W J
authors.initials: BW
authors.lastname: Mol
authors.forename: Peter
authors.initials: P
authors.lastname: Herbison
mesh_terms: D001723:Birth Rate; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D007246:Infertility / Q000628:therapy; D008297:Male; D016017:Odds Ratio; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data*; D011247:Pregnancy; D018873:Pregnancy Rate; D027724:Reproductive Techniques, Assisted / Q000706:statistics & numerical data*