A new report from the Centers for Disease Control and Prevention (CDC) suggests that abortion rates in 2015 reached their lowest level in 10 years, although limitations in data collection make it difficult to assess actual abortion numbers in the U.S.

The CDC has monitored the number of women who seek a legal abortion since 1969, and relies on voluntary reporting of abortion statistics from the areas being studied. The CDC's analysis covered the years 2006-2015.

The analysis found a range of abortion rates in 2015 across different areas of the U.S. - from 2.8 abortions per 1,000 women aged 15–44 years in South Dakota, to 23.1 abortions per 1,000 women in New York.

A total of 638,169 abortions for 2015 were reported to CDC, leading to a ratio of 188 abortions per 1,000 live births. This is compared to over 1.4 million abortions in 1990.

The data suggested a decrease in the number of abortions among women 15-44 by 26 percent, and an overall decrease in the number of abortions per 1,000 live births by 19 percent, compared to 2006.

The majority of women who had abortions in 2015 were in their 20s. Nearly 60 percent of those who had abortions in 2015 were women who had given birth before, and nearly half had had abortions before.

The analysis notably does not include data on the number of abortions performed during 2006–2015 in the states of California, Maryland, and New Hampshire. The report notes its own limitations, stating that these three states "did not provide CDC data on a consistent annual basis."  

"During the period covered by this report, the total annual number of abortions reported to CDC was 68%–71% of the number recorded by the [Planned Parenthood-aligned] Guttmacher Institute through a national census of abortion providers," the report reads.

California is the most populous state in the U.S. and has almost no laws restricting abortion.