1. Guttmacher Institute. Unintended pregnancy in the United States.https://www.guttmacher.org/fact‐sheet/unintended‐pregnancy‐united‐states#. Published January 2019. Accessed March 11 2020.
2. Declines in Unintended Pregnancy in the United States, 2008–2011
3. Centers for Disease Control and Prevention (CDC). Contraception: birth control methods.https://www.cdc.gov/reproductivehealth/contraception/index.htm. Published November 1 2019. Accessed February 10 2020.
4. U. S. Department of Health and Human Services (HHS) Office of Population Affairs (OPA). Pregnancy prevention birth control methods.https://www.hhs.gov/opa/pregnancy-prevention/birth-control-methods/index.html. Accessed February 10 2020.
5. US Department of Health and Human Services (HHS) Office of Population Affairs (OPA). Pregnancy prevention birth control methods IUD.https://www.hhs.gov/opa/pregnancy-prevention/birth-control-methods/iud/index.html. Accessed February 10 2020.