Answer: Yes!

According to the Guttmacher Institute, up to 57% of unplanned pregnancies are conceived while using a contraceptive.

Symptoms of viral STD's can be treated, but they recur and are infectious for life. Men and women who have any STD are up to five times more likely to contract HIV, the virus that causes AIDS.

• Pelvic Inflammatory Disease (PID) in women, which may cause infertility and could cause an Ectopic Pregnancy (a pregnancy growing outside of the uterus)
• Cancer, which can lead to death if undetected

U.S. Department of Health and Human Services.   (1997).   Fertility, Family Planning, and Women’s Health: New Data from the 1995 National Survey of Family Growth.  23(19).  Retrieved from: http://www.cdc.gov/nchs/data/series/sr_23/sr23_019.pdf
Jones, S. K., Darroch, J. E., & Henshaw, S. K. (2002).  Contraceptive Use Among U.S. Women Having Abortions in 2000-2001.  Perspectives on Sexual and Reproductive Health, 34.  Retrieved from: http://www.guttmacher.org/pubs/journals/3429402.html