Some couples or individuals decide that adopting a child represents the best way of dealing with infertility. Others elect to utilize the services of a surrogate mother—a woman who contracts with a couple to carry their fetus to full term, deliver it, and adopt it to the couple. A physician may artificially inseminate the surrogate with the man's sperm or implant an in vitro fertilized egg into her uterus. Either way, the procedure remains controversial, given the many potential ethical, legal, and moral issues it raises. For example, questions of legal, moral, and biological parenthood can give rise to long and complicated custody proceedings.
Similar to surrogate motherhood, and also controversial, is carrier implantation. The procedure involves implanting a fertilized egg into a relative's uterus. Because a relative carries the fetus to term, the woman or couple avoids the expense and hassle of hiring a surrogate mother. Physicians have now successfully implanted embryos into women in their 50s, following hormone therapy to reverse the effects of menopause.
Sex preselection techniques designed to help a couple choose the gender of their unborn child have also proven controversial. Because sperm bearing the Y chromosome produce males, couples wanting a male baby attempt to increase the chances of a Y‐bearing sperm fusing with the X‐ovum. A number of sperm‐separating techniques supposedly accomplish this. For example, doctors can impregnate the mother‐to‐be via artificial insemination of primarily Y‐bearing sperm, which they have separated in a test tube. Success rates of sperm‐separating techniques are questionable, with reported figures approaching 85 percent. Critics note that society cannot know the effects of gender imbalances created through sex preselection. Will people prefer more girls than boys? What happens to the future of marriage and family?
Perhaps even more presumptuous (or alarming, according to some critics) than reproductive technologies and sex preselection is altering human behavior through genetic engineering. Cloning, or the creation of exact replicas from a single genetic ancestor, represents the most extreme form of genetic engineering. Geneticists have cloned animals for years, but may soon focus their efforts on human beings.
One of the latest advances in genetic engineering is gene therapy, in which genetic engineers, in limited cases, can disable genes carrying undesirable traits and replace them with genes carrying desirable traits. While these sorts of developments pose many possibilities for altering various organisms and eradicating certain diseases and disabilities, gene therapy remains experimental.
For obvious reasons, certain groups, such as the National Multiple Sclerosis Society and the Cystic Fibrosis Foundation, support genetic engineering in the hopes of dramatic cures being developed. Still others, like certain religious groups, oppose genetic engineering.