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NEW YORK - As the U.S. Supreme Court prepares to hear a religious dispute over the Obamacare contraception mandate, advocates on both sides are trying to set the court straight on the science.
The case, to be heard on March 25, is one of the most closely watched of the year, partly because it taps into the enduring debate over abortion and reproductive rights.
The dispute turns on the legal question of whether corporate employers with religious objections must include contraceptive coverage in their employee health plans. But it also raises a scientific dilemma that could influence the court's nine justices.
That scientific question is deceptively simple: whether certain forms of birth control prevent conception or destroy a fertilized egg. After decades of research the answer is not absolutely clear.
Two family-owned companies, Oklahoma-based arts-and-crafts retailer Hobby Lobby, controlled by evangelical Christians, and Pennsylvania-based cabinet-manufacturer Conestoga Wood Specialties Corp, owned by Mennonites, object on religious grounds to a requirement of President Barack Obama's healthcare law: that employer-sponsored insurance cover contraception.
The companies say they have no objection to covering forms of birth control that prevent conception, the fertilization of an egg by a sperm.
What concerns them are after-intercourse products, so-called emergency contraception such as the "morning-after" pill, which prevent pregnancy.
Anti-abortion groups contend the products act after fertilization, destroying embryos.
"For us, the issue is the life-ending mechanisms that some emergency contraceptives can have," said Anna Franzonello, an attorney at Americans United for Life, an anti-abortion legal group that has filed a brief for seven Catholic and other anti-abortion groups siding with the companies.
Mainstream scientific and medical organizations, as well as abortion-rights supporters, counter by citing research showing that the vast majority of emergency contraceptives prevent fertilization.
While the Supreme Court will not be ruling on the science, and has never defined pregnancy, many groups have filed friend-of-the-court briefs offering their view of how emergency contraceptives work.
The basics of pregnancy are clear, although the language of ending pregnancy is fraught with politics.
After an egg is released, it has about a day to find a sperm to fertilize it. Sperm survive several days before losing their ability to join with an egg. But the union of egg and sperm is merely the first step: if a fertilized egg does not burrow into the lining of the uterus, there is no pregnancy. In fact, in an estimated 50 percent to as many as 80 percent of conceptions the fertilized egg fails to implant.
The Obama healthcare law, known as the Affordable Care Act, requires coverage of "contraceptive methods," but not drugs which cause an abortion - that is, end pregnancy.
Medical groups including the American College of Obstetricians and Gynecologists as well as federal health agencies say pregnancy begins with implantation. That's what allows James Trussell of Princeton University, an expert on reproductive health, to say that emergency contraception "won't cause an abortion in the legal and medical sense of the word."
That infuriates people who believe life and pregnancy begin with fertilization. "There is a segment of the medical field that says there isn't a human life until the baby has implanted," said Dr Kathleen Raviele, an ob-gyn in Tucker, Georgia, and spokeswoman for the Catholic Medical Association. The group supports Hobby Lobby and Conestoga. "You have two groups talking past each other."
The Hobby Lobby and Conestoga families want to protect an egg from the moment of fertilization, since they believe preventing implantation ends a life, and they object to the three approved forms of emergency contraception:
* Copper intrauterine devices (IUDs), a form of contraception that has only been used as an after-sex emergency contraceptive about 7,000 times since 1976.
* All forms of Teva Pharmaceutical Industries Ltd's Plan B, a morning-after pill now sold as Plan B One-Step and available over-the-counter to those 15 and older. It has the vast majority of the emergency contraception market in the United States.
* Prescription-only ella, from the Watson Pharma unit of Actavis PLC, which has a tiny share of the U.S. market.
Supporters of Hobby Lobby and Conestoga cite studies that, they believe, support their position that emergency contraceptives prevent implantation. Supporters of Obamacare's contraception mandate point to the larger and growing number of more recent and more rigorous studies showing that emergency contraception almost always acts by preventing fertilization.
Complicating the dispute, the positions of drug regulators and manufacturers have changed over the years.
The evidence is strongest that copper IUDs can prevent implantation of a fertilized egg. The T-shaped devices are most likely to work if inserted well before ovulation, suggesting that their main mechanism of action is disabling sperm or eggs, preventing fertilization. But if fertilization already has occurred, an IUD can prevent implantation, said Kristina Gemzell-Danielsson of the Karolinska Institute in Sweden, who has reviewed more than 100 studies of emergency contraception.
PLAN B PILLS
The U.S. Food and Drug Administration for years implicitly has buttressed the idea that Plan B interferes with implantation. In 1999, it approved a label saying the drug can prevent implantation of a fertilized egg. In a 2009 document on its website, the FDA still said, "If fertilization does occur, Plan B may prevent a fertilized egg from attaching to the womb (implantation)".
Since then, however, the International Federation of Gynecology & Obstetrics, which includes the ob-gyn groups of 125 countries, reached different conclusions. In a 2012 analysis of 29 rigorous studies, the organization concluded that the active compound in Plan B, levonorgestrel, primarily acts by preventing or delaying ovulation. The drug does that by inhibiting a hormone surge that allows ovarian follicles to develop and release an egg.
Plan B is most likely to prevent pregnancy in women who take it before ovulation, said Gemzell-Danielsson.
All told, "there is very, very clear and compelling evidence that Plan B does not work after fertilization," said Princeton's Trussell.
Late last year, European drug regulators recognized that scientific understanding had changed since levonorgestrel came on the market: they approved changing the label of the version of Plan B One-Step sold in Europe to say that it "cannot stop a fertilized egg from attaching to the womb."
It is unclear if the FDA will follow. Spokeswoman Erica Jefferson said, "The agency is aware of emerging data that suggests that (Plan B's compound) does not inhibit or prevent implantation of the fertilized egg and acts only by blocking or delaying ovulation, but has not had the opportunity to formally evaluate this recent data."
A spokeswoman for the drug's manufacturer, Teva, declined to comment.
ELLA AND IMPLANTATION
There have been fewer studies of ella. When the FDA approved it, in 2010, the agency said that although ella is thought to work "primarily by stopping or delaying the release of an egg," it "may also work by preventing attachment (implantation) to the uterus."
A document from manufacturer Watson says "it is possible that ella may also work by preventing attachment (implantation) to the uterus." Watson spokesman David Belian said that language described the company's current understanding.
Researchers who study contraception say that does not reflect current science. Studies show that, like Plan B, ella has no effect on the uterine lining, and mainly works by preventing or postponing ovulation, said Gemzell-Danielsson. But "mainly" is not good enough for those who believe life begins at conception. The tiny chance that ella will prevent implantation of a fertilized egg is, they say, enough to make it morally objectionable.
IS SCIENCE ENOUGH?
Ultimately the two sides may expect different things from science.
"If you can't be absolutely sure the drugs don't block implantation, what probability of killing a human being would you accept?" said Dr Jane Orient, an internist in Tucson, Arizona, and spokeswoman for the libertarian, anti-abortion Association of American Physicians and Surgeons, which joined the anti-emergency contraceptive brief.
"In science, you can't prove a 'never happened' or a 'never could happen,'" responded Dr Timothy Johnson, professor of obstetrics and gynecology at the University of Michigan.
(Additional reporting by Joan Biskupic; Editing by Howard Goller and Peter Henderson)