Guys may now have another reason to get off the couch: Watching TV has been linked to lower sperm counts.

ncreasing fathers' support during pregnancy may lower rates of premature babies and babies born too small.

Sex. Many (but not all) animals do it.

Treating the country's 110 million STDs comes with a price tag of $16.7 billion a year.

From the neurobiology of attraction to the hard truth about online dating, these five books offer fresh takes on our quest for love.

Cohabitating doesn't provide the same health benefits for gay couples that marriage does for straights.

We're all looking for happiness, which is why these late-in-life courtships are so inspiring.

On March 21, the American Academy of Pediatrics announced its support for gay marriage, as well as foster care and adoption rights for same-sex couples.

As the Supreme Court prepares to hear arguments in two gay marriage cases, it's easy to forget how far opinions have moved on the issue.

Here are the key facts about the cases and what's behind them.

Thanks in part to shows like 'Modern Family,' a majority of Americans are now in favor of same-sex marriage.

A federal judge has ordered the Food and Drug Administration to make the morning-after pill available to teens without a prescription.

But rolling in the hay resumes as doctors treat her allergy to semen.

Though childbirth is frequently spoken of in terms of pain and punishment, some women do experience what are known as orgasmic or ecstatic births.

The same-sex marriage rulings by the Supreme Court are but the most recent in a long history of cases that reshaped the family structure.

Research suggests that long-distance relationships encourage more communication and that couples try harder.

New research concludes that hypersexuality is not a neurological or physiological disorder, but just heightened libido.

Women who have had heart attacks want more information than they're currently getting from their cardiologists in order to move on with their lives.

Despite the HPV vaccine being effective at preventing infections and cancers down the line, just one-third of teen girls complete the injection series.

Male primates may have become monogamous to protect their offspring from being killed by rival males.

Videos and ads by Roxy for women's surfing gear and swimsuits anger female surfers.

Feeling happy? Go ahead and smile — but know that you may be telling others more about yourself than you think.

Keeping sperm from being ejaculated may provide the key to creating a birth control drug for men.

Confirming a bit of conventional wisdom, a new study finds that people who fear being single often settle for less in love.

Even water tastes sweeter when you're in love, new research finds.

Most middle-aged women do not give up sex as they age, especially if sex is important to them.

Unlike many humans, some monkeys are genuinely faithful to their mates.

The popularity of weird beards and mustaches among young men living in Brooklyn, N.Y., may be more than just a hipster fad.

Men have lost most of the genes originally included on the Y chromosome during evolution, but those genes essential for survival have persevered.

Certain female spiders are infamous for eating their partners after sex, but some actually pounce on suitors, fangs first, before mating.

Although syphilis was nearly eliminated from the U.S. about a decade ago, the sexually transmitted disease has resurged in recent years.

More than two-thirds of healthy Americans have a human papillomavirus (HPV) infection on some part of their body

"Sex in the Wild" is an entertaining, educational, explicit and scientifically stimulating look at how animals reproduce.

The number of teenage girls and boys in the United States who have received the vaccine remains "unacceptably low" says the CDC.

Early data suggest the U.S. teen birth rate hit a historic low in 2013, according to a new report from the CDC.

Though the study's assumption of what "better" sex means is pretty specific.

Male chimpanzees that wage a campaign of sustained aggression against females sire more offspring than their less violent counterparts.

Picking a partner while on the Pill might have lasting ramifications on marital satisfaction, new research finds.

A new survey links a fondness for grilled cheese with how often you make love. (Seriously.)

If you're looking for a boost in happiness, having more sex may not be your best bet.

Two chubby marsupial species that would literally die for sex (albeit 14-hour sessions) have been discovered in Australia.

Study found that men who ejaculated more than 21 times a month were significantly less likely to develop prostate cancer.

Women's cheeks get redder when they are the most fertile, but this color change is so subtle that it is undetectable by the human eye.

Cancer-causing human papilloma virus, or HPV, can be spread through kissing and oral sex.

Rise of the robosexuals: What will it mean for our human relationships?

A brightly-colored fungus found only on Hawaiian lava flows might be the most powerful aphrodisiac ever discovered.

From the researcher who discovered peacock spiders, a new Australian spider species engages in a complex game to determine if a potential mate is a virgin.

Men now outnumber women in some Scandinavian countries, and scientists are reeling to explain why.

A newly discovered mechanism in the throats of mice works like a supersonic jet engine.

Moorland hawker dragonfly demonstrates the lengths women must go to avoid the opposite sex.