When Pam Lemke and Wendy Rockwood have lunch, they talk about the baby that's due in July. Rockwood, 38, is pregnant. But Lemke, 27, a real estate agent in Redondo Beach, Calif., also has a stake in this pregnancy: She donated the egg that helped create the fetus.

Stunning advances in reproductive technology have made both Lemke and Rockwood the mother of the same child. Doctors retrieved an egg from Lemke's ovary, fertilized it in a laboratory with sperm from Rockwood's husband and then reimplanted the fertilized egg in Rockwood's womb, where it will grow and develop and she will give birth as though the baby were her own.

Lemke supplied the genetic material for the baby while Rockwood will bear the child. Lemke's role, she says, will be limited to that of egg donor; Rockwood and her husband will be the child's legal parents. Nevertheless, there is an extraordinary relationship between the two women who have worked together to create a child.

"I really feel connected to Wendy and that we could be good friends," said Lemke. "But then again, I don't want to be intruding. It is their child. I think that we will be like the kind of people who send Christmas cards to each other."

In some ways, donating eggs is the female equivalent of sperm donation, the technique that, for decades, has enabled women married to infertile men to become pregnant. There are essential differences between the two procedures: Giving eggs is much more difficult than donating sperm; it requires weeks of daily drug injections culminating in an invasive medical procedure to extract the eggs. It demands a greater commitment by donors and poses a greater risk to them as well. And it is far less successful than sperm donation in leading to the birth of a child.

Most important, the new technology is redefining notions about motherhood and raising a host of ethical, psychological and legal questions for donors, recipients and the children they produce.

So far, there is no legislation to cover the legal ramifications of egg donation. Left unresolved is whether an egg donor has any rights to the child -- or whether the child has a right to know the identity of the donor who is its genetic mother. One controversial issue that has already divided reproductive specialists is the question of known vs. anonymous donations. Should, for example, donors and recipients meet and get to know each other, as Lemke and Rockwood did? Or should donation be confidential, as is the case in sperm programs?

Despite these unanswered questions, egg donation is a growing enterprise, practiced at nearly 50 clinics nationwide, according to the American Fertility Society. Each attempt costs about $9,000. Because multiple tries are often necessary for success, some couples take out second mortgages to foot bills that can reach six figures before a child is conceived.

And for many couples, egg donation is a failure. Fertility experts estimate that the overall success rate is about 35 percent -- roughly the same as having a child by the usual method of in vitro fertilization (IVF), the test-tube baby technique.

Despite the cost and the low success rate, the procedure has caught on so fast that statistics have not kept pace. In 1989, the most recent year for which figures are available, more than 100 babies, including 25 sets of twins and three sets of triplets, were born through the procedure, according to the American Fertility Society. In major cities such as Los Angeles, the numbers have probably increased. Eighteen months ago, only two of L.A.'s 17 infertility clinics offered egg donation. Today, all of them provide it, according to Mark Sauer, chief of the egg donation program at the University of Southern California.

At first, those who used egg donation were primarily infertile women whose ovaries no longer functioned as a result of genetic problems or treatment for disease such as cancer. But more recently, a study by the New England Journal of Medicine showed, the procedure could help women past menopause bear children.

In addition, egg donation can boost the success rate for older women trying to have a baby through in vitro fertilization. In IVF, a woman's egg is extracted and mixed with her husband's sperm and then re-inserted into her womb. But the success rate is only about 10 percent for women over 40, in part because their eggs may not be as viable as those from a younger woman.

Some fertility experts, such as Daniel Navot, director of the in vitro fertilization program at Mt. Sinai Hospital in Manhattan, estimate that "several hundred thousand infertile women" might be able to bear children through the procedure.

That requires doctors to find enough healthy, young women willing to donate their eggs. The Search for Donors

Egg donors are motivated by a variety of reasons: Some do it to help their infertile relatives; others need money, and a few say they consider donation a personal mission to aid infertile couples.

Ideally, doctors look for a woman "between 25 to 30 years of age who has a stable marriage, children of her own and probably feels that she had completed her family already," said Mt. Sinai's Navot. But such women are hard to find given the current trends toward later marriage and childbearing.

Donors must be willing to undergo some discomfort, risk and uncertainty. Egg donation poses a slight chance of infection, so there is a small risk that it could cause infertility. Whether repeated donations could harm a donor by speeding up the age at which she undergoes menopause is not known. "There's no evidence that it will accelerate their menopause," said Sauer. Even so, women who donate "are advised that it is an unknown," he added.

Many programs minimize the risk to donors by accepting only women who have completed their own families. Or they harvest eggs from women who are already undergoing surgery for other reasons, such as sterilization.

Other donors have successfully undergone in vitro fertilization in which several eggs are extracted to boost the opportunities for a test-tube pregnancy. Once the process is completed, leftover eggs can be donated. Most programs also allow directed donations, involving sisters or other relatives.

But the reality is that no more than half of all egg donors fall into these so-called "ideal" situations -- the reason a growing number of programs advertise.

Even then, only a small percentage of applicants are accepted as donors. At Mt. Sinai Hospital in New York, for example, more than 250 women responded in writing to an ad for egg donation. But only about 15 went through the program, Navot said. The others were eliminated at various phases of screening.

To attract young, healthy, fertile women who want to help -- and are interested in the compensation -- fertility programs often place ads such as this one in college newspapers:

"Healthy Women Wanted As Egg Donors. Help infertile couples. Confidentiality ensured."

One senior in economics at George Mason University in Fairfax read this ad for egg donors in The Broadside, the campus newspaper, "about 10 to 15 times" last summer before she phoned the Genetics & IVF Institute in Fairfax to ask about becoming an egg donor.

While she has discussed egg donation with her friends, she hasn't told her parents about her donation -- the reason she requested that her name be omitted. "I don't want them to think, 'Gee we can't afford to put {our daughter} through graduate school, so she's having to sell her body parts,' " she said.

She spent the two weeks before her donation studying for finals and giving herself daily injections of medication: A shot of the drug Lupron, a synthetic hormone, under the skin of her arm each morning blocked the natural signals from her pituitary to her ovaries so that doctors could carefully control ovulation, the moment when her eggs are ready to burst from the ovary. Injections of Pergonal, a fertility drug, in her thigh each evening stimulated her ovaries to produce large amounts of eggs. For the five days before her donation, she arrived at 7:30 a.m. at the institute for mandatory blood tests that gauged precisely how close to ovulation she was, thereby telling doctors the best time to retrieve her eggs.

She says she endured the shots, the inconvenience, the blood tests, the poking and prodding to earn tuition for graduate school in economics. She'll be paid $1,500 for each donation, which will supplement the money she earns as a part-time bartender. "I'd be lying if I didn't tell you that I'm doing it for the compensation," she said. "I expect to stay in the program for a while." Anonymous Donation

Physician Maria Bustillo, who performs egg donation at the Genetics & IVF Institute, insists on running the program anonymously. The few exceptions are relatives who decide to donate to each other.

When Bethesda clinical psychologist Linda Cimarusti screens potential egg donors for the institute, she starts with the standard questions about serious psychiatric illness, alcoholism and drug abuse. Then she looks for instability and impulsiveness. Donors who decide quickly to give eggs may regret the decision later. Those who are going through a personal crisis are also eliminated, because the added stress of donation could be detrimental to their mental health.

Prospective donors who cancel and reschedule appointments or are chronically late signal trouble to Cimarusti. Some may be ambivalent or too disorganized to follow the regimen necessary for successful egg retrieval.

Most who arrive at Cimarusti's office are healthy students, seeking to pick up some extra cash. Some need money for tuition, others have overspent their credit cards.

"Some of them feel very good about what they are doing," said Cimarusti. "But I'm not sure that they would do it just out of the goodness of their hearts."

Technically, donors don't sell their eggs. They are paid for time and transportation, which can add up to two weeks of daily visits to the clinic, plus a day of egg retrieval. At most programs, payment is $1,500, the rate that the American Fertility Society suggests is fair compensation for a donor's inconvenience. Some programs pay as much as $2,000 and as little as $1,000.

Prospective donors take a battery of psychological tests, including the Minnesota Multiphasic Personality Index and the Rorschach ink blot tests.

During the psychological assessment, Cimarusti judges how important payment is, if potential donors have any religious concerns about their donation that might later trouble them and whether they plan to tell anyone about their participation. Women who tell no one harbor a secret that could grow more important with time and be difficult to handle emotionally, Cimarusti said. It is best, she said, when donors confide in a few close friends or relatives.

Advocates of anonymous donation say that the less involved a donor is with a recipient, the less invested she is in the outcome -- minimizing the possibility of problems later.

"Can the person truly give this egg as a piece of genetic material and no more?" Cimarusti asked. "Hopefully, {a donor} won't spend lots of time in the future wondering, 'Do I have a child or not?'

"People can be told that six eggs were retrieved, that sort of thing, but I think that it is better not to know more," she said.

Bioethicist John Fletcher of the University of Virginia agrees that donors should not become psychologically involved. "If you decide to donate, that is enough," he said. "You need not set yourself up for emotional entanglements that are avoidable." Donors' Motivations

While most programs are committed to anonymous donation, a growing number allow donors to meet the recipients of their eggs.

Lemke has done it both ways. She donated her first egg anonymously last August. To Lemke, who is not yet ready to start a family of her own, the act was an extension of her other volunteer activities: giving blood regularly and raising money for the American Cancer Society.

The donation also had a psychological reward, she said, in helping her work through her grief over the deaths of several close relatives and friends in the past several years. "It's helping to bring life into the world," she said. "The prospect was really, really exciting for me."

After the egg retrieval, Lemke was curious to know whether the recipient became pregnant but afraid she would be disappointed. "I know the success rates are not so good," she said. "I didn't want to find out that it didn't work."

She learned the answer when the nurse from the center called to tell her that the recipient was pregnant -- with twins. Lemke and her husband celebrated, and after some deliberation she agreed to participate again.

But this time, the couple -- the Rockwoods -- wanted to meet her. "I was really nervous about it," said Lemke. "When you don't know the person, it's a little easier to sever the ties. But I decided to go ahead and meet her. I was really nervous about it."

At the meeting, prospective recipient Wendy Rockwood and her husband, Chuck, greeted her with a rose. The donation occurred in November. Two weeks afterward, tests confirmed that Rockwood was pregnant.

Sauer, the USC physician who has performed egg donations for more than six years, said that most of his patients favor open over anonymous donations. A meeting can reassure both donors and recipients, he said. Recipient couples want to know more about the donors than is available in questionnaires. Donors also get a chance to see the prospective parents.

Sauer's program screens donors, then matches them with an appropriate recipient and has them contact each other. "From a physician's point of view, it's much easier to orchestrate," he said.

Those who participate in such open donations say that the experience gives them the chance to extend their family and relationships in unimaginable ways.

Susan Scott of Monrovia, Calif., a suburb of Los Angeles, has undergone nine egg donations, a record for the USC program. Four children have been born from her donations, including a set of twins. One more baby is on the way.

Her only requirement is that she must meet and stay in touch with the recipient couples. "It's not necessarily typical, but it's the way that I choose to do it," she said. "It's what I get out of it."

Scott, 33, is married and has two children. To Scott, the distinction between being a parent and being an involved egg donor is clear.

"I want pictures annually," she said. "I don't want to babysit or be invited over to dinner, but I want to know that things are okay forever."

Often, she is invited to the hospital to see the newborns her eggs have produced. Sometimes, she's there as well when things don't go right. One pregnancy went two weeks beyond the due date. When the baby was stillborn, Scott and the recipient mourned together. Since then, she has helped the woman become pregnant again.

Scott says she understands what it's like to desperately want children. At 23, she was diagnosed with severe endometriosis, an inflammation of the lining of the uterus; doctors told her she could probably never get pregnant. Two years later, she was married and had given birth to her first child, a daughter, after spending most of her pregnancy in bed. In 1985, she had a son.

Shortly afterward, she read about a new infertility program starting at a local hospital. Known as ovum transfer -- a crude precursor to egg donation -- the procedure involves a donor who is artificially inseminated with the sperm of an infertile woman's husband. The fertilized egg is flushed from the donor's uterus before it has a chance to implant. The egg is then transferred to the infertile woman, who carries it to birth.

She underwent ovum donation five times -- all unsuccessfully -- with the same couple. When the egg donor program started, she quickly volunteered.

"You talk to these {infertile} people and hear the anguish and suffering they have had," she said. "They are struggling, desperate and completely powerless to do anything unless a donor agrees to help them."

Scott's husband often takes time off from work to care for their children when she goes for a donation. Her children have met their half-siblings. Her sister, Cheryl Korchak, 34, also donates eggs. Korchak, a lawyer, and her husband have five children. She has donated four times so far and, like her sister, insists on meeting all recipients.

"My husband was adopted," Korchak said. She sees herself as keeper of the genetic records for the children that result from her donations as well as her own. Besides, she said, if a recipient couple "doesn't want to know me, they don't want to know my child."