The use of the emergency morning-after contraceptive pill has increased by more than 5 percent among U.S. women in the last decade.

In 2002, 4 percent of the U.S. female population was found to be using the emergency morning after contraceptive pill. Over the last ten years, this number has increased to 5.8 million, which accounts for 11 percent of overall sexually active women in the country, suggests a Centers for Disease Control and Prevention report released Thursday.

Among these women, 59 percent said they used the pill just once.  24 percent of these women confirmed using the contraceptive drug twice while another seven percent said they used it three or more times.

Since 1999, these pills have been available by prescription in the U.S. A certain type of the morning after pill - Plan B, created a huge controversy when it was launched. The drug works like any other contraceptive pill and stops the release of a woman's egg, thus preventing pregnancy. However, it needs to be taken within a few days of intercourse.

After years of debate, in 2006, the U.S. Food and Drug Administration allowed women above the age of 21 to buy the pill without a prescription and later reduced the age limit to 17 years.

While women groups supported the decision calling it a useful way to prevent unwanted pregnancies, conservative groups opposed it saying it could lead to more sexual assaults and promiscuity.

According to the study findings, hispanics and blacks used the pills more than whites after having unprotected sex. Also women who had a lower education background used the pill more than women who were highly educated.

"The women who are less likely to have access to healthcare are more likely to say 'I didn't use another method, and I turned to emergency contraception to protect myself,'" said Amy Allina of the National Women's Health Network.