1. From the Centers of Disease Control and Prevention;MMWR Morb Mortal Wkly Rep,2002
2. The economic impact of multiple-gestation pregnancies and the contribution of assisted-reproduction techniques to their incidence;Callahan;N Engl J Med,1994
3. Birth weight standards for triplets under modern obstetric care in the United States, 1984-1989;Elster;Obstet Gynecol,1991
4. The changing epidemiology of multiple births in the United States;Russell;Obstet Gynecol,2003
5. Contribution of assisted reproductive technology and ovulation-inducing drugs to triplet and higher-order multiple births–United States, 1980-1997;MMWR Morb Mortal Wkly Rep,2000