(7 of 8)
The most controversial of the new methods of reproduction does not depend on advanced fertilization techniques. A growing number of couples are hiring surrogate mothers (see box) to bear their children. Surrogates are being used in cases where the husband is fertile, but his wife is unable to sustain pregnancy, perhaps because of illness or because she has had a hysterectomy. Usually, the hired woman is simply artificially inseminated with the husband's sperm. However, if the wife is capable of producing a normal egg but not capable of carrying the child, the surrogate can be implanted with an embryo conceived by the couple. This technique has been attempted several times, so far without success.
The medical profession in general is apprehensive about the use of paid surrogates. "It is difficult to differentiate between payment for a child and payment for carrying the child," observes Dr. Ervin Nichols, director of practice activity for the American College of Obstetrics and Gynecology. The college has issued strict guidelines to doctors, urging them to screen carefully would-be surrogates and the couples who hire them for their medical and psychological fitness. "I would hate to say there is no place for surrogate motherhood," says Nichols, "but it should be kept to an absolute minimum."
In contrast, in-vitro fertilization has become a standard part of medical practice. The risks to the mother, even after repeated attempts at egg retrieval, are "minimal," points out Nichols. Nor has the much feared risk of birth defects materialized. Even frozen-embryo babies seem to suffer no increased risk of abnormalities. However, as Steptoe points out, "we need more research before we know for sure."
The need for research is almost an obsession among IVF doctors. They are eager to understand why so many of their patients miscarry; they long to discover ways of examining eggs to determine which ones are most likely to be fertilized, and they want to develop methods of testing an embryo to be certain that it is normal and viable. "Right now, all we know how to do is look at them under the microscope," says a frustrated Gary Hodgen, scientific director at the Norfolk clinic.
Many scientists see research with embryos as a way of finding answers to many problems in medicine. For instance, by learning more about the reproductive process, biologists may uncover better methods of contraception. Cancer research may also benefit, because tumor cells have many characteristics in common with embryonic tissues. Some doctors believe that these tissues, with their tremendous capacity for growth and differentiation, may ultimately prove useful in understanding and treating diseases such as childhood diabetes. Also in the future lies the possibility of identifying and then correcting genetic defects in embryos. Gene therapy, Hodgen says enthusiastically, "is the biggest idea since Pasteur learned to immunize an entire generation against disease." It is, however, at least a decade away.