This Week in Sex is a weekly summary of news and research related to sexual behavior, sexuality education, contraception, sexually transmitted infections, and more.

The Pill as a Cancer Fighter

In the decades since the pill revolutionized birth control, there have been fears that use of hormonal contraceptive methods might increase a woman’s risk for certain cancers.

New results from a long-term study should calm many of these fears. The study suggests that birth control pills do not raise a woman’s lifetime risk for breast or cervical cancer once she stops taking it. But the protective factors the pill provides for ovarian, endometrial, and bowel cancer can last for decades.

The study, conducted by the United Kingdom’s Royal College of General Practitioners, began in 1968, just a few years after oral contraceptives were introduced. Researchers recruited 46,000 women, both pill users and nonpill users, and followed them for up to 44 years.

They found that women who had taken the pill for any length of time reduced their chances of getting ovarian cancer by 33 percent, endometrial cancer (cancer of the uterine lining) by 34 percent, and bowel cancer by 19 percent. Interestingly, they found that the protective effects of the pill lasted long after the women stopped taking it—up to 35 years.

The study did find a slight increase in the risk of cervical cancer and breast cancer for current pill users, but this was temporary and disappeared within five years of stopping the pill.

The researchers see this news as reassuring to women. Lisa Iversen, the lead author on the study, told the Telegraph: “Because the study has been going for such long time, we are able to look at the very long-term effects, if there are any, associated with the pill. Specifically, pill users don’t have an overall increased risk of cancer over their lifetime and that the protective effects of some specific cancers last for at least 30 years.”

Sex and the College Student

It’s spring, so college-bound high school seniors around the country are waiting to see where they were admitted. As they check the mail for acceptance letters, they may also be pouring over rankings to see which school has the best music program, cafeteria food, dorms, or parties. And, in doing so, they may come across new rankings from collegesstats.com about which campuses are having the most sex. But be careful: These rankings are tied to a misleading “risk calculator.”

The rankings are based on surveys to a sample of 2,000 current students and alumni asking how much sex and how many partners they had as an undergrad.

The results found that both men and women had an average of five sexual partners during their college careers. The website ranked the “20 Most Sexually Active Colleges” based on students’ average number of sexual partners and found Temple University in Philadelphia had the highest with an average of almost 11 partners, followed by Rutgers University New Brunswick with more than nine, and Texas A&M and the University of South Carolina with about eight each. In the bottom of the top 20 were the University of Utah, the University of Maryland, and the main campus of Penn State.

The study also asked about condom use, which was spotty at best. Thirty-eight percent of respondents said they always used a condom, 24 percent usually used a condom, and 14 percent reported sometimes using a condom. A full 15 percent of the college students and alumni said they never used a condom.

Unfortunately, the survey’s results are linked to an STI exposure calculator. Students put in their location, the number of sex partners they’ve had, the number of sex partners they think their partners have had, and their degree of exposure. (The degree of exposure is a number between one and 12. The default setting is six based on the idea that we are all six degrees of separation from each other, but users can change it. It’s unclear how anyone would calculate their own degree of exposure. But the higher it is, the more people to whom you’ve been supposedly exposed indirectly).

Ultimately, the calculator spits back how many people you’ve been “exposed to” and likens this to populations of cities and campuses. According to this calculator, I have been exposed to 15,015 people, which is the equivalent of 67 percent of the campus population at the University of Massachusetts at Amherst (my alma mater ) or 99 percent of the population of Williamsburg, Virginia.

As we said the last time one of these slut calculators—err, sex calculators—reared its ugly head, this kind of fuzzy math means nothing. It is based on your guesses about how many people your partners have had. And it assumes that all sex is equally risky (without asking the gender of your partner, whether you had penetrative sex, and if you practiced safer sex), and treats STI risk as if it were cumulative over a lifetime. If you test for STIs between partners and have none (or test and get treated for a curable infection), you get a clean slate. These calculators just play into—and exacerbate—the stigma attached to having “too many partners.”

Instead of discouraging more partners, collegestats.com should encourage more condom use and routine testing because getting it on while on campus, even with a bunch of different people, is fine as long you protect yourself and them.

Coming to a Smartphone Near You: Sperm Counting

Gone may be the awkward days of men being handed a porn magazine and a cup at the fertility doctor. Researchers at Boston’s Brigham and Women’s Hospital and Harvard Medical School are developing a new device and accompanying smartphone app that could let men check both sperm count and motility (how fast and efficiently they move en route to that all-important egg).

The device attaches to a smartphone, essentially turning the camera into a microscope. A user puts a small semen sample on a disposable microchip and inserts that into the device itself. The app then takes a one-second video of the sperm and analyzes it.

The device can measure sperm count, motility, and velocity, all of which are important to fertility. This can be helpful both for men who want to conceive or those who have had a vasectomy and want to make sure they are no longer releasing sperm. Tests on more than 350 users found that the device was 98 percent accurate even when used by people with no training.

The researchers believe that the device has potential beyond sperm testing. Hadi Shafiee, one of the researchers and an assistant professor in medicine at Brigham and Women’s Hospital at Harvard Medical School, said that similar technology could be used to test blood and saliva for infectious diseases.

Germaphobes, take heart: No sperm comes into direct contact with your phone.