A report by the Centers for Disease Control and Prevention's National Center for Health Statistics found nearly 38 percent of pregnancies in 2004 were to women under age 25 -- down from nearly 43 percent in 1990.

The proportion of pregnancies among teens under age 20 dropped from 15 percent in 1990 to 12 percent in 2004.

The report said there were almost 6.4 million pregnancies in 2004 among women of all ages, about 6 percent fewer than the nearly 6.8 million in 1990. The 2004 total included 4.11 million live births, 1.22 million induced abortions and 1.06 million fetal losses.

"This latest pregnancy outcome report finds that there was little change in births and fetal loss numbers between 1990 and 2004," Stephanie Ventura, head of the Reproductive Statistics Branch at NCHS said in a statement. "However, abortions fell 24 percent over this time period."

Nearly half -- 45 percent -- of the 6.4 million pregnancies in 2004 occurred among unmarried women.