OBJECTIVE - To measure the effect of competition among fertility centers on pregnancy and high-order multiple (HOM) gestation rates after IVF.
DESIGN - Retrospective cohort study.
SETTING - 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.
PATIENT(S) - Three hundred eighty-one fertility clinics reporting clinical outcomes.
INTERVENTION(S) - 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.
MAIN OUTCOME MEASURE(S) - The clinic HOM gestation rate (percentage of pregnancies that were HOM) and age-adjusted pregnancy rate.
RESULT(S) - 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.
CONCLUSION(S) - According to these data, the risk of HOM gestation decreases with increasing competition among clinics; however, pregnancy rates are unaffected.