Lawrence B. Finer and colleagues at the Guttmacher Institute in New York found the rate of U.S. women using highly effective long-acting reversible contraceptive methods increased from 2.4 percent in 2002 to 8.5 percent in 2009.
The increased use of the implant or IUD occurred simultaneously with a decline in both sterilization and the use of less effective short-term methods such as condoms and the birth control pill, Finer said.
The study authors analyzed data from the 2006 to 2010 National Survey of Family Growth and found the highest use of long-acting contraceptive was among women ages 25 to 39 and among women who had at least one child. Just 2 percent of women with no children had used the long-term methods, compared with 15 percent of women with one or two children.
Finer and colleagues speculated low levels of use among young women and among those who have not yet had children could be related to the high up-front costs and provider misperceptions about who may appropriately use he methods.
"The average age at first sex is around 17, and the average age at first birth close to 25 -- the time period during which women are at risk for unplanned pregnancy is much longer than it used to be," Finer said in a statement. "Young women in particular, the group at highest risk of unintended pregnancy, could benefit greatly from these highly effective contraceptive methods, which protect them over a much longer period and which require virtually no user intervention."