title: Effects of competition among fertility centers on pregnancy and high-order multiple gestation rates.
abstract: OBJECTIVE
  To measure the effect of competition among fertility centers on pregnancy and high-order multiple (HOM) gestation rates after IVF.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Four hundred eight fertility clinics registered with the Society for Assisted Reproductive Technology as providing IVF services in 2000. Competition was defined as number of clinics in a geographically defined area. Demand for services was based on the population of reproductive-aged women.
  
  
  METHODS
  Three hundred eighty-one fertility clinics reporting clinical outcomes.
  
  
  METHODS
  Pregnancy rates, HOM gestation rates, population of reproductive-aged women, and number of competing clinics were calculated for each clinic from Society for Assisted Reproductive Technology and census data.
  
  
  METHODS
  The clinic HOM gestation rate (percentage of pregnancies that were HOM) and age-adjusted pregnancy rate.
  
  
  RESULTS
  The number of clinics in an area of competition ranged from 1 to 22. The HOM gestation rate per clinic ranged from 0% to 50%. As demand increased, competition increased. As competition increased, the number of HOM pregnancies per clinic decreased. In areas of low competition (1 to 2 clinics) the clinic HOM gestation rate was 8.43%, in areas of intermediate competition (3-7 clinics) 8.39%, and in areas of high competition (8-22 clinics) 8.24%. In areas with intermediate demand, high levels of competition resulted in fewer HOM pregnancies than intermediate competition (relative risk 0.56, 95% confidence interval 0.36-0.89) or low levels of competition (RR 0.57, 95% confidence interval 0.35-0.94). Age-adjusted pregnancy rates did not differ by level of competition.
  
  
  CONCLUSIONS
  According to these data, the risk of HOM gestation decreases with increasing competition among clinics; however, pregnancy rates are unaffected.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Southern California Keck School of Medicine, Los Angeles, California 90033, USA. asteiner@usc.edu
authors.forename: Anne Z
authors.initials: AZ
authors.lastname: Steiner
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Paulson
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Hartmann
mesh_terms: D000328:Adult; D000554:Ambulatory Care Facilities / Q000191:economics / Q000706:statistics & numerical data*; D000704:Analysis of Variance; D016001:Confidence Intervals; D004465:Economic Competition / Q000191:economics* / Q000706:statistics & numerical data*; D005260:Female; D005307:Fertilization in Vitro / Q000191:economics / Q000706:statistics & numerical data*; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data*; D012189:Retrospective Studies