ATLANTA, Georgia (CNN) -- Doctors don't have to tell 18-year-old "Rose" (who doesn't want to reveal her real name) the importance of using a condom every time she has sex.
"There really is a limit to how much you can trust somebody," the young woman said.
At 14, Rose contracted two sexually transmitted diseases: gonorrhea and chlamydia. She said she got the STDs from her first boyfriend.
"We used condoms at first. Then, me being naïve, we stopped," Rose recalled. "I thought he was only having sex with me."
The STDs went untreated and eventually developed into pelvic inflammatory disease, or PID, a condition that can lead to infertility.
Dr. John Douglas, director of the Centers for Disease Control's Division of STD Prevention, called infertility a "down-the-road concern" for many teens.
He and other doctors worry about sexually active teenagers and young adults who may be unaware that some STDs may doom their chances of having a baby later in life.
He said it is a growing reality for nearly 2 million women in the United States who are infertile.
"We don't know how many are affected by STDs, but they can cause PID. A woman [with PID] has a 10 to 20 percent chance of being left infertile," Douglas said.
Dr. Yolanda Wimberly, an adolescent medicine specialist with Grady Health Systems in Atlanta, Georgia, explained that PID can damage the reproductive organs by creating scarring and inflammation in the fallopian tubes. VideoHealth Minute: Watch more on teens and the infertility risk of STDs »
"It can happen to anyone. It does not discriminate," Wimberly said, referring to both the chances of contracting an STD and the potential for infertility.
Three days a week, she meets with teens and young adults at a health clinic just west of downtown Atlanta. Many of them have one thing in common: a lack of awareness about the dangers of STDs.
"You have the same story coming in over and over again," she said. "It's sad. The names and faces change, but the stories pretty much remain the same." Visit CNNhealth.com, your connection for better living
Wimberly first met Rose when the girl was hospitalized four years ago during her bout with PID.
"It had become a severe infection. ... She was having difficulty keeping anything down," the doctor recalled.
"It hurt so bad. It felt like somebody kept stabbing me in my stomach. I couldn't walk or anything," Rose said.
Doctors treated her with intravenous antibiotics. Both the STDs and PID cleared up.
Then, a year later, when she was 15, Rose was diagnosed with another type of STD called human papillomavirus, the leading cause of cervical cancer.
Doctors removed some abnormal cells from her cervix, which could lead to pregnancy complications in the future.
Rose recovered, and she said she hasn't had any problems in three years, but questions remain about her future ability to have a child.
"I cry sometimes thinking about it, because I want it, but I'm not positive if it can happen," said Rose, who dreams of becoming a mother.
Wimberly tried to reassure Rose by telling her having PID does not automatically lead to infertility.
"But it can decrease your chances of becoming pregnant in the future," Wimberly told her.
Wimberly is reluctant to put young, at-risk women through intensive and expensive fertility testing. Rather, she recommends that when they are older and the time is right, they first attempt to conceive a child on their own.
In the meantime, Wimberly said, she walks a fine line as she deals with her patients' immediate needs, be they birth control, disease prevention or sex education.
Wimberly cautions couples to always protect themselves during sex by using a condom every time.
She also tells young men and women to get checked by a doctor for STDs every six months or every time they change sexual partners.
Finally, Wimberly urges parents to get involved in the discussion and not to be afraid to talk to their teens about the dangers of unprotected sex and the possibility of becoming infertile.
Rose conceded that she learned the hard way.
"I want people to learn from my mistakes so they won't have to go through the same things I went through," she said.
She recently graduated from high school and, prompted by her own health scare, hopes to become a nurse.
Rose also has a new boyfriend and says they "always use protection, no matter what."
"You might be in love and trust someone ... but be smart, think 'what if.' Think for yourself," she said.
