With all the things that parents worry about when it comes to their teens, having risky sex after getting the HPV vaccine shouldn't be one of them.

So says the latest study published in the Canadian Medical Association Journal. The human papillomavirus (HPV) is associated with almost every case of cervical cancer. It can cause head, neck and anogenital cancers, as well as genital warts in men and women.

The Centers for Disease Control recommends two shots of HPV vaccine for girls and boys aged 11 and 12, given six to 12 months apart. They work best when given before teens become sexually active, the CDC says. HPV, which is spread through sexual intercourse, is extremely common in America, affecting about one in four people, according to the CDC.

Apparently, removing the risk of contracting a sexually transmitted disease makes some parents freak.

HPV causes 33,700 cancers in men and women. HPV vaccination can prevent most of the cancers (about 31,200) from ever developing, the CDC reports.

But a primary reason that parents give for not vaccinating their children is that parents are afraid teens will be emboldened by the vaccine and run out and have risky sex. The study's lead author Gina Ogilvie told Newsweek:

"When parents are asked why they are hesitant to have their children receive the vaccine, one of the key issues they identify is the concern that the vaccine will encourage children and adolescents to make poorer sexual health choices."

About the study

Researchers wanted to see if parental concerns that getting the vaccine would lead to promiscuity are true. They tested it by comparing teens' sexual behavior before and after getting the vaccine.

The HPV vaccine program in British Columbia schools began in 2008 for girls in the sixth through ninth grade and those in the sixth grade in 2011. Researchers looked at data from 298,265 girls who completed a survey that asked about their emotional and physical health from the years 2003, 2008 and 2013. The girls all identified as heterosexual.

From 2003 to 2013, the proportion of girls who had sex dropped from 21.3 to 18.3 percent, the study authors wrote. Girls who had sex before the age of 14 and used substances before intercourse "decreased significantly," they said.

Teens today make healthier choices

There was no significant change in the number of sexual partners from 2003 to 2013. Also during that time, pregnancy rates decreased.

"These findings are consistent with studies in Scandinavia and smaller clinic-based studies in the U.S. that confirm that adolescent young women do not make poor sexual health choices after the HPV vaccine," study co-author Dr. Elizabeth Saewyc, of the School of Nursing at the University of British Columbia, told Newsweek. "Teens today make healthier decisions about sex than their older peers — or even their parents."

The most recent study backs up a 2015 study published in JAMA Internal Medicine that the vaccine does not lead to teens to throw sexual caution to the wind. In that study, up to 20 percent of parents worried that their kids would have riskier sex, possibly without condoms if they received the vaccine.

The HPV vaccine is now available for adults

Just this month, the Food and Drug Administration announced that the HPV vaccine is expanding for use for adults up to age 45.

The vaccine is for men and women between the ages of 27 and 45. Previously, the vaccine was only available for those between the ages of 9 and 26.

"Today’s approval represents an important opportunity to help prevent HPV-related diseases and cancers in a broader age range," said Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research. "The Centers for Disease Control and Prevention has stated that HPV vaccination prior to becoming infected with the HPV types covered by the vaccine has the potential to prevent more than 90 percent of these cancers, or 31,200 cases every year, from ever developing."

The HPV vaccine was approved in 2006. The CDC reports that cervical cancer kills about 4,000 women each year.

READ MORE: