Researchers at the Centers for Disease Control and Prevention in Atlanta analyzed data from the 2004 to 2008 Pregnancy Risk Assessment Monitoring System -- self-reported pre-pregnancy contraceptive use among white, black and Hispanic females ages 15-19 with unintended pregnancies resulting in live birth involving 27 states and approximately 75 percent of all live U.S. births.
Fifty percent of these teens were not using any method of birth control when they got pregnant, and of these 31.4 percent said they believed they could not get pregnant at the time.
Twenty-one percent said they used a highly effective contraceptive method, 24.2 percent used the moderately effective method of condoms and 5.1 percent used the least effective methods, such as rhythm and withdrawal.
For the purposes of the study, contraceptive methods were categorized by effectiveness based on published effectiveness rates. Highly effective contraceptive methods included sterilization, IUD, injectable medroxyprogesterone also known as the birth control shot, oral contraceptives, hormonal patch and vaginal ring. The moderately effective category included condoms. The least effective category included diaphragm, cervical cap, contraceptive sponge, rhythm method and withdrawal.
Nearly one-quarter of the teens reported their partner did not want to use contraception, while 22 percent indicated that they would not mind if they got pregnant, 13.1 percent reported having trouble getting birth control and 9.4 percent experienced side effects from contraception, the study said.