The rate of triplet and other higher-order multiple births increased from 37 per 100,000 live births in 1980 to 194 in 1998, largely attributable to increased usage of fertility therapies.
During 1999-2003, the rate of triplet and higher-order multiple births has remained stable.
Older mothers and non-Hispanic white mothers are the most likely to have a triplet or higher-order multiple birth.
[Births: final data for 2003. National vital statistics reports, vol. 54, no. 2. Hyattsville, MD: NCHS; 2005. http://www.cdc.gov/nchs/data/nvsr/nvsr54/nvsr54_02.pdf; Reynolds MA, Schieve LA, Martin JA, et al. Trends in multiple births conceived using assisted reproductive technology, United States, 1997–2000. Pediatrics 2003;111:1159?66; 20Oct05, CDC, MMWR]