The December report did not tabulate unintended pregnancies, though preliminary information from the Centers for Disease Control and Prevention found a slight increase in the birth rate in 2003, most notably in women older than 30.
Physicians, statisticians and advocates who specialize in reproductive health had several theories for the rise in unprotected sex. They pointed to possible factors such as gaps in sex education, the cost of birth control, declining insurance coverage, fears of possible side effects of contraceptives and personal attitudes about childbearing.
It is possible, said Paul Blumenthal, that many more women are trying to conceive and thus have stopped using contraception. But the Johns Hopkins University professor said it is more likely that more women have found the cost of birth control burdensome.
"Because the number of uninsured has increased, these women might be on the short end of that stick," he said. Since 2001, the number of uninsured Americans has risen by 4 million.
Jeffrey Jensen, director of the Women's Health Research Unit at Oregon Health and Science University, said he regularly encounters patients who have trouble affording birth control, even if their private insurance covers it.
"It is absolutely unconscionable that women have a co-pay of $20 or $25 [a month] for contraceptives and men are getting off scot-free," Jensen said. Drug companies "have cut way back" on free samples and many women turn to less effective types of birth control because of cost, he said, "running a greater risk of pregnancy as a result."
Of the 34 million women in need of contraceptive services -- those who are not sterilized, pregnant or trying to conceive -- about 17 million qualified for publicly funded care, according to a 2002 report by the nonprofit Alan Guttmacher Institute. Of that number, 6.7 million received government-funded services, most through Medicaid or the Title X family-planning program.
But Title X "is nowhere near keeping up with inflation," said Susanne Martinez, vice president of public policy at the Planned Parenthood Federation of America. Adjusted for inflation, the program's 2003 budget was 57 percent smaller than it was in 1980, she said. In addition, Title X dollars are now spent on a broader range of services, such as testing for sexually transmitted diseases.
Many physicians put partial blame on federally funded abstinence-only education programs that by law prohibit discussion of contraceptives, except to detail their failure rates.
"We are spending an enormous amount of money on something that hasn't been shown to work," Trussell said. "It's a giant step backwards."