Assisted reproductive technologies: estimates of their contribution to multiple births and newborn hospital days in the United States.

Objective: Estimate the contribution of assisted reproductive technology (ART) in the United States to multiple gestation births and newborn hospital days.
Design: Analysis of successful ART conceptions occurring during 1990 to 1991 compared with vital statistics. Newborn hospital days are estimated from the 1990 National Hospital Discharge Survey.
Setting: The American Fertility Society and the Society for Assisted Reproductive Technology registry.
Patients: Infants delivered from ART.
Interventions: Assisted reproductive technology.
Main Outcome Measures: Number of multiple gestation infants and newborn hospital days.
Results: Approximately 12,327 live-born infants were delivered from ART conceptions during 1990 to 1991, representing 22.2% of all live-born triplet, 17.3% of quadruplet, and 11.4% of quintuplet infants born in the United States. The number of newborn hospital days attributed to ART infants was 87,135 days. Between the periods 1972 through 1974 and 1990 through 1991, the rate of triplet and higher order multiple gestation infants per 100,000 white live births increased by 191%, with 38% due to ART conceptions and 30% to increased childbearing among older women.
Conclusions: Assisted reproductive technology contributed 22% of U.S. triplet and higher order multiple births during 1990 to 1991.