While many states have aggressively restricted access to abortion, most of those laws were adopted in the past two years and are not believed to have played a role in the decline.
Abortions have been dropping slightly over much of the past decade. But before this latest report, they seemed to have pretty much leveled off.
Nearly all states report abortion numbers to the federal government, but it’s voluntary. A few states, including California, which has the largest population and largest number of abortion providers, don’t send in data. While analysts estimate there are more than 1 million abortions ­nationwide each year, the CDC counted about 785,000 in 2009 because of incomplete reporting.
To come up with reliable year-to-year comparisons, the CDC used the numbers from 43 states and two cities — those that have been sending in data consistently for at least 10 years. The researchers found that abortions per 1,000 women of child-bearing age fell from about 16 in 2008 to roughly 15 in 2009. That translates to nearly 38,000 fewer abortions in one year.
Mississippi had the lowest abortion rate, at 4 per 1,000 women of child-bearing age. The state also had only a couple of abortion providers and has the nation’s highest teen birth rate. New York, second to California in number of abortion providers, had the highest abortion rate, roughly eight times Mississippi’s.
Nationally since 2000, the number of reported abortions has dropped overall by about 6 percent and the abortion rate has fallen 7 percent.
By all accounts, contraception is playing a role in lowering the numbers.
Some specialists cite a government study released this year suggesting that about 60 percent of teenage girls who have sex use the most effective kinds of contraception, including the pill and patch. That’s up from the mid-1990s, when fewer than half were using the best kinds.
Experts also pointed to the growing use of IUDs, or intrauterine devices, T-shaped plastic sperm-killers that a doctor inserts into the uterus.
A study released this year by the Guttmacher Institute, a nonprofit organization that does research on reproductive health, showed that IUD use among sexually active women on birth control rose from less than 3 percent in 2002 to more than 8 percent in 2009.
IUDs essentially prevent ‘‘user error,’’ said Rachel Jones, a Guttmacher researcher.
Ananat said another factor may be the growing use of the morning-after pill, a form of emergency contraception that has been increasingly easier to get. It came onto the market in 1999 and in 2006 was approved for non-prescription sale to women 18 and older. In 2009 that was lowered to 17.
Underlying all this may be the economy, which was in recession from December 2007 until June 2009. Even well ­afterward, polls showed most Americans remained worried about anemic hiring, a depressed housing market, and other problems.