The president wants us to think of ourselves as “former embryos.” That phrase was on the T-shirts worn by some of the babies appearing with him last month as he underscored his opposition to a bill supporting the use of embryos for stem-cell research.

If we are former embryos – that is, if our lives begin at the moment an egg and a sperm joined to create an embryo, in or outside the womb, and if we change our national laws to give the embryo full constitutional rights as a human being – then doing anything to destroy any embryo would be akin to murder.

The embryo would be afforded all the dignity granted a child, even if it looked like a glob of cells in a petri dish. It would be a person.

This idea is more than a slogan on a T-shirt. It’s the official position of the Roman Catholic Church and of many evangelical Christians. It’s the law in the state of Louisiana – where the embryo, as a “juridical person,” has the right to sue or be sued – and in Germany and Italy.

Just imagine if the president had his way, and this became the new, official definition of life in America.

We’d certainly have to change a few things.

For starters, abortion would be outlawed. If the earliest stage of an embryo, no more than a cell or two, is accorded full constitutional rights, then surely a fetus would be as well. This would undoubtedly upset the majority of Americans, who wish for abortion to remain a legal option.

Infertility treatments would become all but impossible – astronomically costly and technically difficult. Now, when an egg and sperm are combined in a laboratory to form embryos for implantation in the womb, more embryos than needed are often created. This allows for doctors to play a bit of nature’s role: They can select the embryos most likely to implant successfully, and they can screen out potential abnormalities.

Human reproduction, remember, is highly inefficient. Most fertilized eggs don’t go on to become pregnancies, in nature or in the lab. We’re surrounded by wasted embryos, if you think about it.

But if that were considered murder, if all the embryos had to be used and not frozen or discarded, then the success rate would drop precipitously. Implant more than three embryos at a time and you risk dangerous multiple pregnancies and miscarriages. And you court a range of risks and abnormalities if all screening is outlawed.

Don’t take my word for it. Look at Italy, where Europe’s most restrictive fertility law went into effect last year, requiring that no more than three eggs be fertilized at any one time, all must be transferred to the womb simultaneously, and none can be screened or frozen. The success rate for treatment has declined dramatically. Italians are flocking to other countries for what they can’t get at home. And a huge public outcry has forced a referendum later this month on whether some of the new law should be repealed.

Ironically, Italy has the lowest birth rate in Europe – so low that the government is giving cash bonuses for the birth of a second child. The Italians may need help thinking through the consequences of their laws, as we sometimes do.

Then again, if the embryo were legally a person, we wouldn’t have to worry about low birth rates because contraception would become problematic. Barrier methods such as condoms and diaphragms would, I suppose, be permitted, but certain birth control pills and the IUD would be banned because, as a last resort, they sometimes prevent implantation of a fertilized egg. The protracted argument over the so-called morning-after pill could finally end because that, too, occasionally works after fertilization and therefore would be banned. And forget RU-486, which terminates an early pregnancy.

It seems that the president is ambivalent about contraception anyhow. When asked recently whether he was for or against it, White House spokesman Scott McClellan refused to answer.

The strange thing is that the president, as the father of twins, might be expected to understand how hard it is to draw a bright line defining when life begins. No one can say when Barbara and Jenna Bush got their individual starts in utero; twinning can take place as long as seven to 10 days after fertilization. This is why even some Catholic theologians suggest that “ensoulment” occurs at some time after conception.

One can respect the embryo without granting it full personhood. But that doesn’t seem to suit the president. Life would be simpler in his brave new world. Not for the infertile couple or the sick mother or the rape victim, perhaps, but for the embryo. And in his world, that’s what counts.