Plan B, the "morning-after" contraceptive recently approved for over-the-counter use, is not as effective as a drug company claims, and there is no evidence that the pill's widespread use will reduce the rate of abortions or unwanted pregnancies, argues a Utah doctor who sat on the Food and Drug Administration's advisory panel.

On top of that, Plan B can act as an "abortifacient" — sometimes not preventing fertilization but preventing implantation instead — contends Dr. Joseph Stanford, associate professor of family and preventative medicine at the University of Utah School of Medicine.

This biological nuance is important to people who believe that life begins at fertilization, when the sperm enters the egg, versus others who believe it begins at implantation, when the embryo is implanted in the endometrium.

Stanford hopes that doctors will alert patients that the pill may technically cause an abortion. It's the kind of informed consent only "marginally" addressed in the pill's package insert, he says. "It's the way that it's phrased, to minimize the issue," he adds, referring to the insert phrase "when a fertilized egg implants." At time of implantation, he argues, "the embryo is over 100 cells."

At a medical lecture earlier this week, several doctors in the audience noted that even religious women may be more concerned about preventing an unwanted pregnancy than they are about terminology or how the pill works in their bodies.

One doctor said that when he tells his patients that IUDs may work in a "post-fertilization" manner, "zero patients flinch and say 'I don't want this.' Zero." Religiosity, said another, "may take a back seat" to the desire not to be pregnant, even in Utah.

Another doctor expressed concern about what he called a more important moral issue: that the drug company marketing Plan B may be overstating its effectiveness and therefore "taking advantage of women in a vulnerable situation." Ads for Plan B boast that "seven out of eight women won't get pregnant."

Plan B, approved a month ago for over-the-counter use, can prevent pregnancy if used within 72 hours after intercourse. It is more effective the sooner it is taken, which was the rationale used by the FDA for approving its nonprescription use.

According to its manufacturer, the drug is effective in 89 percent of cases. But Stanford argues that studies done by him and other researchers show a lower effectiveness rate. "We did more a precise meta-analysis that shows it's effective only 72 percent of the time, and even that number is optimistic," he says.