When you use donor eggs, "you tend to have a 50-50 chance of conceiving," Paulson said, so once Mrs. Ward started using donor eggs, "she flipped the coin in November and it came up tails but in April she flipped again and it came up heads and she had twins."
Though the odds of conception increase greatly with the use of donor eggs, fertility specialists say women are often very reluctant to give up on the dream of having a child that shares their DNA.
"We deal with 40- and 42-year-old women all the time who absolutely don't want donor eggs, but the chance is approximately two percent at age 47 of a woman conceiving a child with her own egg," said Silber.
When a couple realizes that they will have to have another woman be the biological mother of their child, and pay thousands and thousands of dollars to do it, "the response might be, 'Well, gee, shouldn't they just have adopted ?'" said Dr. Ellen Clayton, an ethicist and professor of genetics, health policy, pediatrics and law at Vanderbilt University.
"For many people [adoption] is a wonderful choice," she said, but wanting to carry the child yourself is also "a choice that they ought to be able to make."
"There is something really special about being pregnant," she said, "something primal."
"It's very different from adopting," Paulson agreed. "Everyone would rather have a baby from their own egg and their husband's sperm, but if that's not possible, the next best thing after that is that you get pregnant with donor egg."
"With adoption you get to be a parent once the baby is born but with donor egg, you get to be a parent from the moment of conception," he added.
The mother bonds with the child by carrying it for nine months, said Silber, "and whatever question marks she may have had by it not having her DNA are erased by this bonding process."
For this reason, he said he has never seen a couple using donor eggs have problems feeling that the child "was not theirs" once it was born.
Pregnancy holds great emotional significance for many couples. But when fertility treatments fail time after time, is there ever a point when couples should be advised to stop trying?
It's a tough and very personal question, fertility experts say.
"It all depends on the persistence and philosophy and desire of the couple," said Silber.
"It is so hard to be absolutely definitive in telling someone to quit," he said, but sometimes the emotional and financial stress of repeated failed attempts can take their toll on couples and dogged persistence is not always the best option.
Ultimately, age can become a factor as well, says Clayton.
One of the recurring ethical issues with IVF is whether it is fair to the children, she says, to have much older parents, considering that a 46-year-old new mother may not live to see her child graduate college or to see her grandkids.
But "a life with a 46-year-old mom that really wants you is better than not living at all or being an unwanted child," she said. "We need to resist the temptation to demonize [older mothers using IVF] because of their age and their desire to have the sensation of gestation."
And if they're willing to "move with the technology" and use donor eggs if needed, Paulson says, it shouldn't take a quarter of a century as it did for the Wards.
"I really feel that in today's day and age, almost everyone can become pregnant."