Despite periodic media scares, young teens are remarkably unlikely to be sexually active, new research finds. And even older teens are delaying sex more frequently than in the past.

The study, published online today (April 1) in the journal Pediatrics, found that a mere 2.4 percent of 12-year-olds had ever had sex. At 16, a third of teens reported sexual activity, a number that climbed to 71 percent by age 18 and 19.

Low rates of sexual activity among young adolescents have been the norm for decades, study researchers said. Recently, however, older teens seem more inclined to take it slow, too.

"Policymakers and the media often sensationalize teen sexual behavior, suggesting that adolescents as young as 10 or 11 are increasingly sexually active," study researcher Lawrence Finer of the nonprofit Guttmacher Institute said in a statement. "But the data just don't support that concern. Rather, we are seeing teens waiting longer to have sex, using contraceptives more frequently when they start having sex, and being less likely to become pregnant than their peers of past decades." [ Teen Pregnancy Rates by State ]

The findings match earlier studies that put the current teen pregnancy rate at a 40-year low. A report released in 2012 found that teen pregnancies peaked in 1990 and declined 42 percent over the next 18 years. As of 2008, the most recent year data were available, 68 per every 1,000 teens experienced a pregnancy.

Finer and his co-author Jesse Philbin, also of Guttmacher, used nationally representative data from the National Survey of Family Growth to track teens' sexual histories over time. The data come from the years 2006 to 2010.

They found that in any give age group, the likelihood of a teen being sexually active is lower than any time in the past 25 years. What's more, more than 80 percent of 16-year-olds having sex for the first time used contraceptives, the researchers found. A year later, 95 percent of those teens had taken up contraceptive use. Those rates were similar to the numbers seen in teens initiating sex after age 16.

Younger teens had a more troubling pattern, with adolescents who began having sex before age 14 using contraceptives less frequently and taking longer to adopt them into their sexual repertoire.

Another alarming discovery was that of the few young adolescents who reported having sex, many or most did not do so voluntarily. The researchers found that 0.6 percent of 10-year-olds reported having sex; 62 percent of females who said they'd had sex by that age reported that it was coerced.

Similarly, 1.1 percent of 11-year-olds reported having sex, and 50 percent of the females in that group said their first time was coerced.

• 10 Facts Every Parent Should Know about Their Teen's Brain
• Birth Control Quiz: Test Your Contraception Knowledge
• 50 Sultry Facts About Sex 

WASHINGTON - U.S. health regulators said on Tuesday they have approved a drug made by Japan's Shionogi & Co to treat women experiencing pain during sexual intercourse. 

The U.S. Food and Drug Administration approved the drug, Osphena, for a type of pain known as dyspareunia, which is a symptom of vulvar and vaginal atrophy due to menopause.

Dyspareunia is associated with declining levels of estrogen hormones during menopause. Osphena, known chemically as ospemifene, is a pill that acts like estrogen on vaginal tissues to make them thicker and less fragile, resulting in a reduction in pain associated with intercourse.

The drug's label includes a boxed warning, the most severe available, alerting patients to an increased risk of strokes and deep vein thrombosis. Common side effects include hot flashes, vaginal discharge, muscle spasms and excessive sweating.  

ATLANTA - Fewer black women in the United States are being infected with HIV, but the number of young gay and bisexual men infected is rising, the Centers for Disease Control and Prevention said on Wednesday. 

Between 2008 and 2010, the number of newly infected black women dropped 21 percent, according to the CDC report. Yet despite the decline, they still accounted for 70 percent of all new HIV cases among women, the federal health agency said.

The rate of new infections for black women was 20 times higher than the rate for white women, the CDC said.

The number of new infections among young gay and bisexual men increased by 22 percent during that same two-year period, the CDC said.

The number of new HIV infections diagnosed annually in the overall U.S. population remained unchanged between 2008 and 2010 at about 47,500, according to health officials.

Public information campaigns on HIV prevention and testing seem to be working in lowering the number of new infections among African-American women, said Joseph Prejean, chief of the Behavioral and Clinical Surveillance Branch in the CDC's division of HIV/AIDS Prevention in Atlanta.

"We are encouraged to see some declines among African-American women," Prejean told Reuters. "They've been one of the most severely affected populations. We're cautiously optimistic that this could be part of a longer-term trend."

Among young gay and bisexual men, efforts to fight HIV have not been as effective, possibly because of advances in treatment for AIDS, the immune disorder caused by HIV, Prejean said.

"We do realize that many men who have sex with men do probably underestimate their personal risk and believe that treatment advances minimize the health threat," Prejean said.

Even though treatment can prolong the life of an AIDS patient, Prejean cautioned that "their life really does change. They then begin to take medication and will take medication for the rest of their lives," he said.

HIV is an incurable infection that costs $400,000 to treat over a lifetime, CDC Director Dr. Thomas Frieden said last month after another government report showed more than half of young Americans infected with HIV were not aware they had it.

Young people ages 13 to 24 account for 26 percent of all new HIV infections in the United States, the earlier CDC report said.

The report released on Wednesday said nearly two-thirds of new HIV infections in 2010 resulted from men having sex with other men. Young black men who have sex with men account for more new infections than any other subgroup, government health officials said.

"Because gay men account for 66 percent of all new infections, we must increase the focus of our prevention programs for gay men, particularly young and black gay men," said Michael Ruppal, executive director of The AIDS Institute.

Disgust may play a role in a sexual dysfunction that often renders penetration impossible, new research finds, perhaps revealing a psychological component to physical sexual complaints.

Specifically, women with a disorder called vaginismus are more likely than healthy women or women who have other sexual disorders to feel disgust in response to sexual byproducts such as semen. Vaginismus is a condition in which the pelvic muscles involuntarily contract when penetrated; it often prevents penis-in-vagina intercourse entirely. Though the exact number of women affected is unknown, vaginismus is an uncommon condition, according to the National Institutes of Health.

The new results suggest that involuntary disgust could cause this contraction as a defense mechanism, researchers say.

"In this sense, disgust acts as an emotional equivalent to a cold shower," said Mark van Overveld, a postdoctoral researcher at Erasmus University Rotterdam.

Objectively, van Overveld told LiveScience, sex is a disgusting activity. The bodily fluids and contact with body parts involved are often considered gross or taboo. "From that perspective," van Overveld said, "it is actually quite surprising that people even manage to engage in the act of sexual intercourse at all." 

The researchers developed a sex-specific questionnaire, focusing largely on questions such as how disgusting it would be to handle someone else's, or one's own, sexual fluids. They first tested the questionnaire on 762 students and university employees to make sure it accurately measured sexual disgust. They found that it did.

Next, the researchers recruited 39 women with lifelong vaginismus, 45 women with dyspareunia, or pain during sexual intercourse, and 28 men with erectile dysfunction and asked them to fill out the questionnaire. [ Top 10 Stigmatized Health Disorders ]

The answers revealed that women with vaginismus were more likely than healthy participants or men and women with other sexual disorders to report disgust for sexually contaminated items. This suggests a role for disgust in either the origin or the continuation of the disorder, van Overveld said.

What's tougher to say is exactly how the emotion plays into the dysfunction. The disgust could come first, triggering the pelvic muscle clampdown. Or perhaps initial sexual problems contribute to disgust with the process, van Overveld said. But disgust is an important defense mechanism, he said, and the pelvic-muscle tightening could be a reflex akin to vomiting.

Previous studies have found that disgust and arousal work in opposition to one another, with sexual arousal dampening disgust. The current study, published online Oct. 22 in the Journal of Sexual Medicine, also found that even in healthy women, more feelings of disgust were linked to fewer feelings of sexual arousal.

The findings shouldn't be taken as blaming women with vaginismus for their condition, van Overveld warned. For one thing, disgust is not easy to control. For another, women with vaginismus have been shown in previous research to have normal sex drives.

However, learning to deal with disgust could potentially help women with vaginismus lessen their condition, van Overveld said. Current experimental therapies have women gradually practice touching their own genitalia, diminishing negative emotions in a controlled way. It's a therapy similar to those used to cure phobias, such as fear of spiders.

"An important next step would be to look at the relationship between disgust and sexual arousal more closely," van Overveld said. "Can sexual intercourse indeed perhaps be interpreted as a delicate balance between disgust on the one hand and a state of sexual arousal on the other? If so, can we help women with lifelong vaginismus to shift this balance?"

More from LiveScience:

NEW YORK - Despite a widespread belief that sex during the later stages of pregnancy can jumpstart labor, a new study from Malaysia found no differences in the timing of delivery between women who had sex near term and those who abstained.

"We are a little disappointed that we did not find an association," said Dr. Tan Peng Chiong, an obstetrics and gynecology professor at the University of Malaya, and one of the authors of the study. "It would have been nice for couples to have something safe, effective and perhaps even fun that they could use themselves to help go into labor a little earlier if (they) wanted."

Tan said that many women believe intercourse can induce labor, and scientists have proposed plausible biological explanations for why it might help.

For one, semen contains a hormonelike substance called prostaglandin, which is used in synthetic form to induce labor.

Breast stimulation is also thought to hasten labor and orgasm can trigger uterine contractions.

Tan said the belief also probably came from "the deep seated folk perception that intercourse in pregnancy may be unsafe and may cause pregnancy expulsion or miscarriage despite fairly replete evidence to the contrary."

But few studies have ever investigated whether sex really can initiate labor, and the small amount of existing evidence was inconclusive, Tan and his colleagues write in the obstetrics and gynecology journal BJOG.

So they set out to see whether advising women to have sex during the final weeks of pregnancy could help them avoid an induction.

"Labor induction for prolonged pregnancy is common and many women are also tempted for a variety of personal reasons to trigger labor off in the very latter stages of pregnancy," he said.

The researchers invited more than 1,100 women to participate, all of whom were 35 to 38 weeks pregnant (the typical pregnancy lasts 40 weeks) and none of whom had had sex in the previous six weeks.

Roughly half of the women were advised by a physician to have sex frequently as a means of safely expediting labor.

The other half were told that sex was safe during pregnancy, but that its effects on labor were unknown.

The researchers then tracked the women to determine how long their pregnancies lasted and whether they required any medical intervention to start labor.

They found that about 85 percent of the women who were encouraged to have sex did follow the doctor's advice, while 80 percent of women in the other group also had sex.

Women in the group advised to have sex also had it more frequently for the remaining duration of their pregnancies - three times versus two.

But the rates of induced labor were similar in both groups: 22 percent of those advised to have sex and 20.8 percent of the other group had inductions, a difference so small it is likely to have been driven by chance.

Pregnancy also lasted an average of 39 weeks for both groups.

Dr. Jonathan Schaffir, an associate professor of obstetrics and gynecology at The Ohio State University College of Medicine who has studied obstetrical folklore, said the findings offer good support for the idea that sex won't induce labor.

Earlier research had relied primarily on surveys of women about their sexual experiences during pregnancy, but this study was "the first attempt to really randomize the experience, for some to have sex and some to not, which is a very hard thing to do," he said.

Schaffir wouldn't advise his patients to have sex for the express purpose of going into labor, he added, but the study did indicate that there aren't any hazards to it.

"Even though this study did not show any increase in the rate of labor or a decrease in the rate of induction, it helped to cement the idea that having sex is probably safe if you want it," he told Reuters Health.

Tan said the results show that pregnancy evolved to be resistant to disruption.

"Human pregnancy has to be robust to a little adventure like intercourse and unfortunately for our purpose, it seems pretty robust to the very end," he said.

The idea that someone can have a sex addiction has been controversial, but a new study suggests that it is a real disorder, and lays out rules that could be used in deciding who has it.

Hypersexual disorder, as sex addiction is formally known, is under consideration for inclusion in the Diagnostic and Statistical Manual of Mental Disorders (DSM) — the bible of mental conditions.

But first, researchers need to agree on how to define this disorder. For example, under one proposed definition, a person who simply has frequent sex would not be diagnosed with hypersexual disorder, said study researcher Rory Reid, an assistant professor and research psychologist at the University of California, Los Angeles.

But a person whose sexual activities are excessive, frequently used to cope with stress and interfere with their ability to function in daily life may meet the criteria for the disorder, Reid said.

The definition also needs to hold up in the real world, so that health care professionals can consistently apply it when diagnosing patients.

In the new study, researchers found that professionals could use the proposed symptoms of hypersexual disorder to separate people into two groups — those who have a disorder, and others who don't. In addition, health professionals with varied backgrounds, including psychiatrists, psychologists and social workers, generally agreed about how to interpret the definition.

The researchers emphasized that they are not trying to turn common behaviors — such as having a lot of sex, or watching pornography — into disorders.

Rather, people with hypersexual disorder report feeling out of control, and act on their sexual urges while disregarding the repercussions. "They might consider the consequences momentarily, but somehow feel their need for sex is more important, and choose sex even in situations where such choices might cause significant problems or harm," such as job loss, relationship problems or financial difficulties, Reid said.

The results of the study will be sent to the American Psychiatric Association — the organization in charge of putting together the DSM. APA reviewers will then determine whether hypersexual disorder will be included in the next edition of the manual, to be released next summer.

In the study, hypersexual disorder was defined as "recurrent and intense sexual fantasies, sexual urges, and sexual behavior," that had lasted at least six months. Diagnosis requires that these sexual fantasies, urges and behaviors cause the patient distress, or interfere with some aspect of the patient's life, such as the patient's job or social life. To be classified under the disorder, these behaviors must not be brought on by drugs or alcohol, or another mental disorder.

The researchers interviewed 207 people who had been referred to a mental health clinic, without knowing the reasons for their referral. One hundred fifty-two people had been referred for sexual behavior problems, while 20 were referred for substance abuse, and 35 for another psychiatric condition.

Using the criteria for hypersexual disorder, 134 of the patients referred for sexual problems were diagnosed with hypersexual disorder and 18 were diagnosed as having another psychiatric condition or no condition at all. Having a diagnosis of hypersexual disorder was closely linked to patients' scores on separate questionnaires designed to assess sexual behavior, impulsively and susceptibility to stress.

In 92 percent of cases, the professionals agreed on who should be diagnosed with the condition.

The vast majority of patients who were referred for substance abuse problems (19 out of 20) or another psychiatric condition (32 out of 35) were diagnosed with their respective conditions, and not with hypersexual disorder.

Doctors also asked patients to report which behaviors were most problematic for them, including masturbation, pornography viewing, sex with consenting adults, cybersex, telephone sex and frequenting strip clubs.

The majority who were diagnosed with hypersexual disorder said masturbation and pornography viewing were problematic. Some patients reported losing jobs because they could not refrain from these behaviors at work, Reid said.

Patients are likely to say that they engaged in these behaviors despite efforts to try to control them, and with disregard for the physical or emotional harm to themselves or others, the researchers said.

To answer critics who argue hypersexual disorder could be used as an excuse to be unfaithful, Reid said the disorder would not absolve people from the consequences of their behavior.

"Having a disorder didn't help them avoid consequences, such as divorce, but it is advantageous for them when they want to get help and change," Reid said.

Future research is needed to determine whether people with hypersexual disorder have changes in their brain that are similar to the changes seen in people with addictions, Reid said. In addition, studies should determine the prevalence of the condition in the general population, he said.

If hypersexual disorder is added to the DSM, it will be included in the appendix, Reid said. The inclusion of disorders in the appendix is provisional, and requires further research, Reid said.

More from MyHealthNewsDaily:

• Hypersex to Hoarding: 7 New Psychological Disorders
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Contrary to the reassuring catchphrase "size doesn't matter," penis size may matter in bed — but only for some women, and for certain types of orgasms.

A new study finds that women who have frequent vaginal orgasms are more likely than other women to say they climax more easily with men with larger penises. Women who tend to prefer penile-vaginal intercourse over other types of sex also say the same, researchers reported online Sept. 24 in The Journal of Sexual Medicine.

"Male anxiety about penis size may not reflect internalized, culturally arbitrary masculine stereotypes, but an accurate appreciation that size matters to many women — just as men feel legitimate anxiety when they enter the mating market about their intelligence, personality traits, sense of humor, social status, height, wealth, and other traits known to be favored by women across cultures," study researcher Stuart Brody, a psychologist at the University of the West of Scotland, told LiveScience.

But other researchers were less convinced.

"There's such variability in preference," said Barry Komisaruk, who researches female sexual response at Rutgers University. Women who orgasm through vaginal stimulation may indeed prefer longer penises, Komisaruk told LiveScience, but not everyone prefers to orgasm that way. [ 10 Odd Facts About the Female Body ]

"There are so many different factors," said Komisaruk, who was not involved in Brody's study. "Once it gets to the kind of specifics that they're talking about, I get wary."

Both penis size and female orgasm are hot-button topics. There is still scientific debate about whether vaginal and clitoral orgasms are different phenomena. Different nerves carry signals from the vagina and from the clitoris, Komisaruk said, and stimulation of each activates different brain regions. But some researchers argue that vaginal stimulation is simply activating a different, internal, section of the clitoris. Women report different sensations from vaginal and clitoral orgasms, Komisaruk said, but which one women prefer largely comes down to personal preference.

In some cases, female orgasm is even more complex. For example, Beverly Whipple, professor emerita at Rutgers University and one of the discoverers of the G spot, a sensitive area felt through the front wall of the vagina, has found that women with complete spinal cord injuries can sometimes experience orgasm, even though the nerves that carry sensation up the spinal cord from the pelvis have been severed. It's likely that the sensory vagus nerve, which runs in the abdomen but bypasses the spinal cord, is recruited to carry signals to the brain in these cases, Whipple told LiveScience.

Other research has found that abdominal exercises induce orgasm in some women, resulting in pleasurable spasms at the gym.

Brody holds a different view, pointing to studies finding that the ability to orgasm with vaginal stimulation alone is correlated with better psychological functioning, better relationship quality and greater sexual satisfaction.

"Earlier research with a large representative sample also found that women who are made aware in their youth that the vagina is a source of women's orgasm are more likely to develop the capacity for vaginal orgasm. Therefore, those who deny these findings (and insist on maintaining the politically correct party line) are not doing women a favor, but might be injuring women's health and sexual potential," Brody wrote in an email to LiveScience.

In the new study, Brody and his colleagues asked 323 women, mostly Scottish university students, to recall past sexual encounters. They were asked about their recent sexual behaviors as well as how important penile-vaginal intercourse and other sex acts were to them. They were also asked whether penis length influenced their ability to orgasm with vaginal stimulation.

Defining "average" as the length of a 20-pound banknote or U.S. dollar bill, which are 5.8 inches (14.9 cm) and 6.1 inches (15.5 cm) long, respectively, the researchers asked women if they were more likely to orgasm vaginally with a longer-than-average or shorter-than-average penis. [ Macho Man: 10 Wild Facts About His Body ]

They found that 160 of the women experienced vaginal-only orgasms and had enough sexual partners to compare size experiences. Of these, 33.8 percent preferred longer-than-average penises, 60 percent said size made no difference and 6.3 percent said longer was less pleasurable than shorter.

Supporting the hypothesis that size matters, Brody and his colleagues found the women who reported the highest number of vaginal orgasms in the past month were most likely to say that longer was better.

"This might be due at least in part to greater ability of a longer penis to stimulate the entire length of the vagina, and the cervix," Brody said.

"To me, all of this is just so goal-oriented, and it's difficult for me to see researchers setting up another goal [vaginal orgasm] for women to experience," Whipple said.

Whipple argued that sexuality is healthier when focused on the pleasure of acts from cuddling to kissing to other sexual sensations rather than the goal of reaching orgasm.

"I recommend for women to learn about themselves, learn about their body, find what they find pleasurable and enjoy that, as long as it's not exploiting another person," she said.

More from LiveScience:

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