LAKE MARY, Fla. — During a doubles lesson at an Orlando sports club this month, Gigi Fernandez dragged her tennis racket along the service line. She told the women gathered around her to picture the line as the edge of a cliff: they stepped beyond it at their peril.

Fernandez always seemed perfectly positioned on the court, winning 17 Grand Slam doubles titles and reaching No. 1 before retiring in 1997 at age 33. It was only when she tried to have a baby in her 40s that she found herself on the wrong side of the line.

The odds of becoming pregnant plunge for women over 35, but Fernandez, whose grace at the net was often overshadowed by a trigger temper, forged ahead. She was imbued with the world-class athlete’s mind-set that where there’s a will, there’s a way.

Seven unsuccessful fertility treatments later, Fernandez sat with her partner, Jane Geddes, and listened numbly as her doctor said that her eggs were old and that her Hall of Fame tennis career had contributed to her inability to conceive.

“It was crushing,” Fernandez said, adding, “I felt almost like I wished I would have never played tennis.”

Fernandez’s globe-trotting career made it difficult to sustain a long-term relationship. She met Geddes, four years older and an 11-time winner on the L.P.G.A. Tour, the year she retired.

It was a case of opposites attracting. Geddes’s optimistic and easygoing demeanor smoothes Fernandez’s jagged edges. And Fernandez’s passionate nature makes life more vibrant for Geddes, who has degrees in criminology and law and works for the L.P.G.A. Tour. They had been a couple for five years when they decided to have a child, neither dreaming such an elemental desire would become such a nightmare.

“As an athlete, you have this attitude, ‘I can do anything with my body,’ ” Fernandez said. “That’s how you think. So your biological clock is ticking, but you’re in denial.”

Fernandez tells her tennis students to always play the percentages. It is sound advice in matters of reproduction, too.

Dr. David L. Keefe, the chairman of obstetrics and gynecology at New York University Langone Medical Center, said natural fertility rates for women declined gradually from ages 35 to 38 and more precipitously after that.

In a telephone interview, Keefe, who did not treat Fernandez, said he would advise professional athletes in their early 20s to consider freezing their eggs.

Fernandez said: “I would not have done that because I was so psychotic about my body. I would have never risked taking the hormones and the retrieval and dealing with any adverse effects. I wouldn’t even give blood.”

The intense physical stress that world-class athletes subject their bodies to can lead to ovulation dysfunction. Fernandez thought back to all the menstrual periods she missed in her 20s because of her intense training and how, at the time, that proved more a convenience than a cause for concern.

Based on her experience, Fernandez said she would counsel women in professional sports to start planning for motherhood in their late 20s, rather than a decade later as she did.

“I was so selfish in those years,” she said. “I felt like I had to be. I felt like tennis was so all-encompassing.”

It was not until the summer of 2008, using donated eggs and sperm, that Fernandez became pregnant. When she gave birth to twins, Karson and Madison Fernandez-Geddes, in April 2009, two months after her 45th birthday, the vanity plate on her sport-utility vehicle assumed a new meaning: DBLE GLD no longer referred only to her 1992 and 1996 Olympic doubles titles.

From Pro to Parent

Fernandez, 46, a native of Puerto Rico, started playing tennis at 7 and developed quick hands at the net by returning balls her father, Tuto, tossed as if he were feeding a wood chipper. She accepted a scholarship to Clemson and turned pro shortly after making the 1983 N.C.A.A. singles final as a freshman.

Over the next 15 years, Fernandez won 68 women’s doubles titles. Her most successful partnership was with Natasha Zvereva, with whom she won 14 Grand Slam events. They will compete next week in the Champions Invitational at the United States Open.

After retiring, Fernandez, who was inducted into the International Tennis Hall of Fame this year alongside Zvereva, tried on different identities. She became a scratch golfer, earned her real estate license, took classes at the University of South Florida and coached tennis. On the cusp of 40, Fernandez set her sights on motherhood.

“Gigi’s one of those people who is like, ‘I want it and I want it now,’ ” Geddes said. “So it became her greatest challenge.”

Fernandez and Geddes said they spent five years and roughly $100,000 in a quest to become parents.

“My role, as it often is, was to be the cup-half-full person,” Geddes said, adding, “It’s an unbelievable process of low lows and high highs but unfortunately nothing in between.”

With every failed intrauterine insemination or in vitro fertilization attempt, Fernandez became more distraught. Speaking of Geddes, she said, “I think she hated how obsessive and relentless I became with the process and how upset I became after every failed attempt.”

Fernandez recalled one drive home from the doctor when Geddes steered the car to the side of the road, stopped and said: “That’s it. We are done with this.”

Geddes said it was hard to see Fernandez in such distress. “Halfway through it, I told her she had to stop taking all these drugs,” Geddes said. “She was, like, psychotic.”

Fernandez said: “The hormone treatment was intensely emotional. I don’t say I wassuicidal, but I had suicidal thoughts. My thought was, what’s the point of living if I can’t have a child?”

Despite all that she had accomplished in tennis, Fernandez said, “There’s this implication that women are here to bear children, and if you can’t bear children, you’re useless.”

In 2007, the couple tried adoption. Fernandez said she filled out a lengthy questionnaire to begin the process in Florida only to be stopped by the final question.

“It was, ‘What is your sexual preference?’ ” Fernandez said.

When months passed and their papers were lost in a shuffle of caseworkers, they pursued adoption in California. Twice they were chosen by a birth mother in a process Fernandez described as “very anxiety-producing.”

In each case, Fernandez said, they paid the mother’s expenses, including medical costs, food and rent, only to have each change her mind late in the pregnancy.

When the second adoption fell through in the spring of 2008, Fernandez and Geddes were emotionally and financially drained.

“It felt sort of like it’s not supposed to happen,” Geddes said.

A Friend’s Gift

During the time Fernandez and Geddes were focused on adopting, they became friends with Monika Kosc, who was recently divorced and childless. Kosc said her heart ached for the couple, whose distress was palpable.

One day, she asked Fernandez, “What do you need to have a baby?”

“I need eggs,” Fernandez replied.

“I have eggs,” Kosc said. “You can have some of mine.”

Kosc, who was 36, went for mandatory counseling before agreeing to the procedure. She injected herself with hormones for two weeks. In August 2008, she produced eggs that were fertilized with sperm from an anonymous donor. Fernandez’s doctor, Mark P. Trolice, implanted two embryos in Fernandez’s uterus. Fernandez was in New York for the Champions Invitational when she received a voice-mail message from her doctor. She met Geddes at their hotel before calling back.

“When he said ‘You are pregnant,’ we screamed,” Fernandez wrote in an e-mail. “I cried. The entire hallway knew something had happened in our room!!”

As a precaution, Fernandez withdrew from the Open. The twins were delivered byCaesarean section six weeks early because she had developed high blood pressure.

Now Fernandez works from home, scheduling tennis lessons and business meetings for when the twins are at preschool. Geddes, the 1986 United States Women’s Open champion, commutes 40 miles each way to L.P.G.A. headquarters in Daytona Beach and travels extensively.

The trips are the worst, said Geddes, who told of returning from an overseas event last month and getting a cold shoulder from Madison at the airport.

“To see these guys as a family is priceless,” Kosc said, adding: “I see the biggest change in Gigi. It’s not about her. It’s about the kids. She’s so selfless and giving and thoughtful and responsible and down to earth.”

Kosc was speaking from the playroom in the house in the gated community here where Fernandez and Geddes live and where Kosc, a frequent visitor, answers to Auntie. A plastic golf club and a child’s tennis racket were among the toys. On the top of the television, blocks spelling each child’s name flanked blocks that spelled Mama.

Fernandez, Geddes and Kosc sat cross-legged on the floor, playing with Karson and Madison and talking about their unusual bond.

“I feel like no matter what we do for Monika, we’ll never repay her,” Fernandez said.

Madison and Karson’s eyes were glued to the television, where a cartoon monkey was explaining baseball, basketball, golf, soccer and tennis. The instructional DVD, the sporting version of Baby Mozart, is called “Baby Goes Pro.” It is the brainchild of Fernandez and her business partner, Valerie Stern.

The idea came to Fernandez as she pondered ways to nurture a love and aptitude for sports in her children, who have none of their athletic parents’ genes.

“I really deep down wish they were genetically mine,” Fernandez said. “Sometimes, I kid myself into thinking they are. Because I carried them, I feel so connected to them.”

Geddes, with input from Fernandez, chose the sperm donor based on his personality. In their home office, they keep a folder that contains all the information they have on him. His answers to a questionnaire suggest that he is kind, smart, optimistic and easygoing. He seems a lot like Geddes in temperament, just what the couple was seeking.

Kosc said she has been approached by other couples seeking an egg donor.

“It’s not going to happen,” she said, adding, “I don’t want any half-siblings out there.”

Fernandez interjected, “Only if I want another one.”

Kosc: “You have a perfect world.”

Fernandez: “There is no such thing as perfect.”

Geddes: “That’s the world of Gigi right there.”