IUDs are not a particulary preferred form of birth control in the U.S. (estimates say about 8% of women use them), but they're growing in popularity. And now, Bloomberg reports, they've got an unexpected champion: the Buffett family (yes, of billionaire investor Warren Buffett fame). According to a feature from Bloomberg's latest issue, titled "Warren Buffett’s Family Secretly Funded a Birth Control Revolution," the Susan Thompson Buffett Foundation has been quietly providing seed funds for research on lowering the cost of IUDs, along with studies and initatives meant to increase access to and overage usage of the device. "Very few people will discuss The Anonymous Donor on the record, but tax filings, medical journal disclosures, and an archived interview with a foundation official show the funds come from Warren Buffett, the chairman and chief executive officer of Berkshire Hathaway, and his family," Karen Weise writes in the feature. Recent news out of Colorado points to just how well IUDs can work: That state provided teens and poor women with IUDs and saw its teen pregnancy rate drop by almost 50%. Now, of course, Colorado Republicans have stripped that program of its funding, but the devices remain a favorite of gynecologists and public-health specialists. “Close to 50% of pregnancies in this country are unintended," said Barbara S. Levy, M.D., the Vice President of Health Policy at The American College of Obstetricians and Gynecologists. "Having a remarkably effective contraception option that doesn’t require daily thought or use is a great advantage for women." More effective than condoms and less hormonally invasive than other implants or oral pills, IUDs also have the benefit of being long-lasting, which also makes them highly cost-effective over time. In other words: winner, winner, chicken dinner. Yet — in spite of the fact that Obamacare covers IUDs — it can still be tough for women to make the switch. According to Bloomberg's recent reportage, that's in part because they are expensive to stock, particularly in the more rural areas of America. Luckily, these days the cost of an IUD is going down, creating greater opportunity for women and clinics to gain access to the devices.