Scientists could be one step closer to developing a birth control pill for men. A drug that stunts sperm production aced tests in mouse testes. And if it's proven to be safe and effective in humans, it could expand the prophylactic pool -- an exciting prospect at a time when roughly half of U.S. pregnancies are unintended.
But with the burden of pregnancy falling largely to females, some women say they wouldn't count on it alone.
"I think it depends on both the woman and the man," said Amy McCarthy, a 23-year-old web editor from Dallas. For McCarthy and her boyfriend of two years, Dave, the pill for men would be a welcome addition to the contraceptive repertoire.
"Dave is just as worried about the possibility of pregnancy as I am," McCarthy said, explaining that they already "double up" on birth control methods. "If anything, this is a really empowering development for men. Up until this point, they only had a few options to prevent getting their partner pregnant."
Such options, including condoms and spermicides, can help prevent pregnancy by stopping sperm in their tracks. But researchers at Columbia University Medical Center in New York City say the drug BMS-189453 can quickly and reversibly stop sperm production. Developed more than 10 years ago as a possible treatment for skin and inflammatory diseases, the drug's sperm-stunting potential was originally considered a toxic side effect.
"One company's toxin may be another person's contraceptive," said Debra Wolgemuth, a professor of genetics as well as obstetrics and gynecology at Columbia University Medical Center in New York City and lead author of the study published June 4 in Endocrinology, in a statement.
Sperm production ramped up again when the mice stopped taking BMS-189453, and the drug did not appear to hamper their libido -- a troublesome side effect reported with other, hormone-targeting versions of the pill for men under development. But some doctors say the idea of quashing sperm production, even temporarily, can be scary for men.
"Sperm-making is a pretty delicate thing, and people do seem to have a concept of that," said Dr. Joseph Alukal, director of male reproductive health at New York University's Langone Medical Center. "How long did it take for women to get comfortable with the reversibility of the birth control pill? I'm not sure."
Nevertheless, Alukal said he thinks some men would welcome the option of a birth control pill.
"If you look at vasectomy, I there are plenty of men in committed relationships who choose to take onus of reproductive planning on themselves," Alukal said. "I think the same sorts of people would choose to look into something like this."
But for single guys, the pill might not fly.
"In modern society, there are all kinds of legitimate questions raised about the utility of a pill like this," Alukal said. Questions like, "Do you really expect guys to take, and their female partners to trust that they've taken it?"
"If I were dating around, though, there's no way I would trust someone that I'd been on just a few dates with [to take the pill]," she said. "I think for most men it just wouldn't be a thought that crossed their mind -- they're worried about getting HIV or gonorrhea, not having a screaming baby."