ATLANTA, Jan. 4 (UPI) -- One in every 30 babies born in the United States in 209 was a twin, compared with one in every 53 in 1980, federal health officials say.
Joyce A. Martin, Brady E. Hamilton and Michelle J.K. Osterman of the National Center for Health Statistics -- part of the Centers for Disease Control and Prevention -- said the twin birth rate rose 76 percent from 1980 through 2009, from 18.9 to 33.3 per 1,000 births, mostly due to mothers having children at an older age and getting fertility treatments.