(CNN) - Abortion rates in the United States have dropped to their lowest level in 10 years, according to a report released Wednesday by the US Centers for Disease Control and Prevention.
From 2006 to 2015, the year of the latest completed survey, reported abortions from participating areas fell 24%, from 842,855 to 638,169.
Going back to 1969, the CDC has completed its "abortion surveillance" to measure the number and characteristics of women who obtain legal abortions. Requests for information go out to the central health agencies in all 50 states, plus Washington and New York City. The most recent surveillance included voluntary abortion data from 49 areas, the exceptions being California, Maryland and New Hampshire.
What researchers found was a striking decrease from where abortion rates were a decade ago. In addition to the steep drop in the number of reported abortions, the rates fell in two other categories. The number of abortions among women 15-44 went down 26%, from 15.9 to 11.8 abortions per 1,000 women. And the number of abortions per 1,000 live births went down by 19%, from 233 to 188.
Compared with the previous year, 2014, there was a 2% decrease in abortions across the three measures.
Because reporting is voluntary and requirements for reporting vary across the country, the CDC acknowledges that the findings have limitations. The number of abortions reported to the CDC, for example, is 68% to 71% of the number established in a census of abortion providers by the Guttmacher Institute, a research and policy group focused on reproductive health and rights, the report says.
But still, the findings offer significant insights into how abortion is trending in the United States.
"The new CDC report shows a continuation of long-term declines in abortions," said Rachel Jones, principal research scientist at the Guttmacher Institute. "Analyses have suggested that improved contraceptive use played a role... In some states, decreased access to abortion services contributed as well."
Who's getting abortions
The majority of women who had abortions in 2015 were in their 20s; 31.1% were aged 20-24 and 27.6% were aged 25-29.
While decreases in abortion rates were seen across all age groups, the greatest decline over the decade was seen in adolescents. The rate of abortions in those aged 15-19 fell 54% between 2006 and 2015, the report shows.
More than 59% of those who had abortions in 2015 were women who'd given birth before. More than 14% were women who'd had three or more births.
A large percentage of women who had abortions in 2015 had had abortions before, according to the latest study. Nearly 44% had had one or more previous abortions; more than 8% had had three or more.
Based on areas that reported race and ethnicity data, the largest percentages of abortions in 2015 were had by non-Hispanic white women (36.9%) and non-Hispanic black women (36%). Hispanic women accounted for 18.5% of all abortions in 2015, while non-Hispanic women of other races made up 8.7%.
When and how are they getting abortions
Nearly two-thirds of all abortions in 2015 were performed at no later than eight weeks of gestation. More than 91% of abortions happened at 13 weeks or less of gestation.
Over the decade surveyed, the percentage of abortions performed at 13 weeks or more remained low, staying at 9% or less. And the percentage of earlier abortions increased, with those occurring at six weeks or less going up by 11%.
Early medical abortion, a nonsurgical abortion at 8 weeks or less gestation, accounted for nearly 25% of abortions in 2015. Of those that were eligible for this method, which uses medications, nearly 36% of women opted for this approach.
More than 64% of abortions were performed surgically at 13 or less weeks' gestation. About 9% were performed surgically after 13 weeks' gestation.
Surveillance of legal abortions in the US helps "to guide and evaluate the success of programs aimed at preventing unintended pregnancies," the report says.
According to the most recent study, unintended pregnancies in the United States have gone down from 51% in 2008 to 45% in 2011-2013.
The rate of abortions can be influenced by a number of factors, the report shows, including availability of contraception, information and health care; access to abortion providers; changes in laws; and shifts in the economy and in attitudes about things like nonmarital childbearing.
Lowering the number of both unintended pregnancies and abortions often go hand-in-hand, the study shows.
And you can't talk about unintended pregnancies without talking about abortions, said Jones of the Guttmacher Institute.
"Affordable access to the full range of contraception and family planning options is critical for people deciding if and when they'd like to become parents, develop their careers, plan for their futures, and manage their health," she said. "For women who become but do not want to remain pregnant, access to safe, legal abortion services remains critical."
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