When Louise Brown was born in Manchester, England, 30 years ago this week, she changed the world of reproductive science.
Brown, who now lives in Bristol, England, was the world's first test tube baby. At the time the process scared a lot of people, conjuring up images of science fiction movies and allusions to "Brave New World" by Aldous Huxley.
There were fears these test tube babies would be outcasts, social pariahs or freaks.
Brown's life has dispelled all those fears. She is all grown up and perfectly normal, and her life has helped to legitimize in vitro fertilization.
Since her birth, more than 3 million babies have been born through IVF, in which the egg is fertilized outside the body and then implanted in the womb.
When asked about the significance of her birthday to the world of science, Brown responded, "The fact that it has helped so many people, I mean, it's a nice feeling that perhaps if I wouldn't have been born, then those children wouldn't be here."
But today IVF isn't just about helping infertile parents. Now it's being used to make sure babies are born healthy.
The therapy is called pre-implantation genetic diagnosis or PGD. It works by screening the embryos for genetic diseases before implanting them in the womb.
Dr. Zev Rosenwaks, director for the Center for Reproductive Medicine and Infertility at Cornell University, says the number of patients coming in and asking for PGD is increasing every year.
"We believe that medicine in general is an endeavor, is a discipline, that in effect aims at relieving pain and suffering and we look at PGD as another form of medicine which allows us to remove a major disease from a given family," Rosenwaks said.
It works like this: embryos are separated out and analyzed. Only the embryos that are healthy, with no sign of the mutated gene that could manifest disease are then kept and grown.
PGD changed everything for Larry and Anne Zimmerman. Larry was born with a rare form of hereditary eye cancer, and when their first born, Perry, was only seven weeks old, tumors starting showing up in eyes and two years later in her brain.
The child spent many months in the hospital and had two operations and is now cancer free, but the ordeal took its toll on the Zimmermans. They wanted more children, but couldn't deal with another cancer diagnosis.
Larry Zimmerman said without PGD he and his wife would never have had their other kids.
"I don't think with what we were going through with Perry's brain tumor that we would have had it in us to basically roll the dice again and hope that we didn't have to deal with this a second time," he said. "It was too painful."
But PGD raises some big ethical questions, especially as scientists identify more and more of our genes: Should parents really have control over the biological make-up of their child?
"How are we ever going to stop people from saying, 'You know what, I'd like someone with musical ability, I would like someone who's mathematically gifted. I want someone who's a good athlete," said Art Caplan, head of the Bioethics center at the University of Pennsylvania. "This slippery slope needs to have some stairs put on it if we're going to have any control over where we're going."
Today there is no legal restriction that would prevent a potential parent from using PGD to pre-determine the gender of their child or to screen for non-fatal diseases or erratic behaviors, if they can find a doctor willing to do it.