Variations on this routine include donor insemination of woman and egg donation. The female sibling of a woman made incapable of childbearing by the loss of a uterus has carried the children of her sister, whereby the aunt gives birth to her own niece or nephew.

These uses of reproductive tissue, which often satisfy an understandable longing for children, raise particular legal considerations. Surrogate parenting is not trafficking in human flesh, but courts have regulated the terms and conditions of the payment of money in exchange for the service.

Women who donate eggs generally receive much more money than a sperm donor because the extraction of a female ovum is much more demanding and difficult than the collection of sperm. In general, the man who donates sperm and the woman who donates ova have no legal standing with reference to the children that may result. (This does not mean, however, that sperm and egg donors may remain anonymous. Records of these donations, which are often made a genetic banks, have been sought by people who have resulted from these conceptions.) Some sperm banks limit the number of donations that a man can make.

Couples who contract for the conception and birth of a child by way of a third party -- that is, a gestational mother -- are well advised to review the contract for this with an attorney. Likewise, women who become surrogate mothers are advised to undertake the arrangement with a written contract.

These unconventional uses of the very stuff of life raise, not only legal considerations, but also very human ones. A few years ago, for example, a New Jersey woman who was artificially inseminated in contract arrangement made headlines when she changed her mind after giving birth to the child she wanted to keep and rear on her own. The woman bonded the daughter she has planned to give to the contracting father and his wife, who then planned to adopt the child.

In divorce actions, courts have been asked to decide the disposal (or distribution) of reproductive tissue -- embryos, sperm and ovum -- that divorcing couples have stored in genetic banks. In general, courts have held that the wishes of a partner who does not wish to use this material for reproduction prevail over the party who does.

In theory today, that child born whose existence was contracted for has three women and two men playing significant roles in his or her conception, birth and nurturing. These technological leaps push family law in new directions, and the law and the courts trail behind the technology.

See also ART; Gamete Provider.