Impact of assisted reproductive technology on the incidence of multiple-gestation infants: a population perspective.

To study the value of a population view in assessing assisted reproductive technology (ART) multiple-gestation infants.Descriptive comparison of ART treatment and population statistics in seven developed countries (United States [U.S.], South Korea, United Kingdom, the Netherlands, Australia, Belgium, Denmark) with varying ART utilization and single-embryo transfer (SET) rates.Not applicable.Not applicable.None.The contribution of ART multiple-gestation infants to the total number of multiple-gestation infants in a population was calculated in relation to utilization of ART and SET rates.The number of ART treatments leading to embryo transfer varied from 304 per million inhabitants in the U.S. to 1,518 in Denmark. The percentage of ART cycles that utilized SET varied from 8.8% in South Korea to 53.3% in Australia. Reflecting both utilization rates and SET rates, the percentage of multiple-gestation infants in the population attributed to ART ranged from 14.7% in South Korea to 29.0% in Denmark.In seven countries, the contribution of ART multiple-gestation infants to all multiple-gestation infants varies from 14.7% to 29.0%, a percentage that was influenced by both the SET rate per cycle and ART utilization rates. In the monitoring of safety and efficacy of fertility treatment, registration of the percentage of SET cycles alone might not be sufficient.