The rate of unintended pregnancies in the United States declined 18% between 2008 and 2011 after a long interval of minimal change, and it is now at the lowest level in 30 years, according to a report published online March 2 in the New England Journal of Medicine.
This “substantial” reduction occurred across all ages, ethnicities, income levels, education levels, and religious affiliations. However, large disparities among demographic groups were still present in 2011, the most recent year for which national data are available for analysis.
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“In particular, poor, black, and Hispanic women and girls continued to have much higher rates of unintended pregnancy than did whites and those with higher incomes. Much more progress can be made in eliminating these disparities,” wrote Lawrence B. Finer, Ph.D., and Mia R. Zolna of the Guttmacher Institute, New York.
National rates of unintended pregnancies haven’t been examined since 2008. To update these figures, the investigators analyzed information from the National Center for Health Statistics, the National Survey of Family Growth, and others.
They calculated that there were 6.1 million pregnancies in the United States in 2011, of which 45% (2.8 million) were unintended. The rate was 45 unintended pregnancies for every 1,000 women of childbearing age in 2011, compared with 54/1,000 in 2008, which corresponds to an 18% decline (N Engl J Med.2016;374:843-52. doi: 10.1056/NEJMsa1506575).
“This was the first substantial decline since at least 1981,” the investigators wrote.
Abortion rates remained steady during the study period. In 2011, the percentage of unintended pregnancies that ended in abortion was 42%, compared with 40% in 2008.
Although the study was not designed to determine the reasons for the decline, several possible factors deserve consideration, according to the investigators. Changes in sexual behavior are unlikely to have driven this reduction, since the incidence of sexual activity tends to remain static over time; changes in the composition of the population also aren’t likely causes, since the demographic subgroups who have higher rates of unintended pregnancy actually increased during this period, the investigators said.
Changes in the desire for pregnancy may have contributed a small amount to the decline, as surveys showed that many women said they would reduce or delay their childbearing during the recent economic recession.
The most likely explanation for the decline, the investigators wrote, is a change in the frequency and type of contraceptive use. Several studies have reported that women at high risk of unintended pregnancy increased both their use of any contraception and their use of highly effective long-acting methods, particularly IUDs.
This study was supported chiefly by the Susan Thompson Buffet Foundation, with additional support from the Guttmacher Center through a grant from the National Institutes of Health. The investigators reported having no other relevant financial disclosures.