We've had test-tube babies, we've had grandmothers giving birth -- and now we have a man, Arnold Schwarzenegger, getting pregnant.
Instead of biceps, it's Mr. Schwarzenegger's belly that bulges in his latest movie, "Junior," in which he plays a fertility researcher who bears a baby. Only in Hollywood? Maybe not. Fertility experts say the idea, although risky, is technically possible.
In rare cases, some women without uteri have had babies. So it's only a little more of a stretch -- so to speak -- for men to do the same.
"It seems far-fetched," says Dr. G. David Adamson, director of Fertility Physicians of Northern California. "But people flying seemed far-fetched a hundred years ago, too.
"One could argue that if you line up 100 men who volunteered today and you treated them with hormones and implanted embryos . . . there's an extremely high probability that one of them, maybe more, could deliver a live baby," Dr. Adamson says.
Theoretically, there are ways for men, given the right female hormones, to develop a placenta without a uterus. Men as well as women have the omentum, a sac of connective issue in the abdominal cavity that could hold the developing embryo and placenta. If a fertilized egg were implanted in the omentum, and the man given strong doses of estrogen and progesterone, the embryo could develop in the abdominal area, growing the placenta around itself, just as it does in the uterus.
But there are many problems with the approach, fertility experts say. Although placenta can form and grow in the abdomen, the uterus is much more accommodating to it, enabling the placenta to tap into the mother's circulation system, which feeds nutrients and oxygen to the fetus. Without the nutrients and oxygen, the fetus most likely would die before birth.
Women who have conceived and borne children without a uterus have faced daunting odds that their baby -- or they -- wouldn't survive. According to medical studies, about 80 percent of the babies don't live, and their mothers' risk of death ranges from 0.5 percent to 18 percent.
Even if the baby is born healthy, the mother can die in childbirth when the placenta separates from the abdominal wall. The heavy bleeding that results is minimized when a uterus is present and contracts, but without a uterus the bleeding can be prolonged and even fatal.
Moreover, the female hormones a man would have to take in order to grow a placenta would cause other troubling changes to his body.
"If you pump a man full of estrogen . . . the man will start developing breasts. Before you know it, you'd have all sorts of other problems," said Dr. Christo Zouves, medical director of the Pacific Fertility Center in San Francisco.
In "Junior," Mr. Schwarzenegger takes "Expectane," an experimental drug with female hormones, so he can carry a baby, but he does not grow breasts. That's Hollywood.
Most fertility experts living in the real world outside Hollywood say they aren't interested in trying to create male pregnancy. At least not yet.
"It will almost certainly be possible to . . . implant it in a man who is hormonally prepared. The baby would almost certainly start to grow," says Dr. Adamson, who has offices in San Jose and Palo Alto, Calif. "But why would anyone do this? There would be massive risks to anyone who undertook to participate in such a study."
Dr. Zouves agrees: "Just because something's technically feasible doesn't mean we should do it."
Both doctors said the procedure was so medically risky that it would be unethical, and possibly illegal.
Still, they acknowledge many of the pioneering aspects of in-vitro fertilization now considered mainstream medicine were once frowned upon as immoral and unethical, too. Many aspects of fertility treatments, Dr. Zouves says, were "all things that were born out of what was a preposterous idea at one point."
If researchers ever learn how to transplant a uterus, which Mr. Adamson says is conceivable in the future, childbearing could become less risky, and thus more likely, for men. So far, that has been impossible because the drugs necessary to accommodate a transplant are toxic to a fetus.
Dr. Zouves thinks "Junior" is better seen as a fable than as science fiction, telling us how much some men -- even macho ones -- want to have children. When a couple battles infertility, it can hurt the man as much as the woman.
"The male partners, inside, feel just as much anguish and pain and loss of control over this event as the women do," he says. "But cowboys don't cry. Men are supposed to be macho."