CUPERTINO, Calif. -- An increasing number of parents are opting to save their newborn's umbilical cord blood. While doctors say it contains stem cells that could provide a powerful treatment should the child later fall ill, some wonder if that security is worth the high price.

Molly and Tom Sherman of Cupertino are in their 30s and perfectly healthy. So are their two sons.

But now the family faces what could be a life-or-death decision. Involving their boys' future health, particularly that of another child.

Molly is pregnant with a third child, and the Shermans are considering doing something they did not do with their other children: banking their new baby's umbilical cord blood to preserve the precious stem cells it contains.

"If something would ever happen to our child, that those stem cells would be there," says Molly Sherman.

"I want to do anything I can as a father to help my family," agrees her husband.

Carrie and Michael Jabs' younger daughter Emma had a rare, but serious stroke three years ago when she was still an infant. It damaged a significant part of her brain, affecting the right side of her body.

Last month Emma had an experimental treatment at Duke University in North Carolina. Doctors infused Emma's own saved stem cells back into her body with the hope they'll re-grow damaged brain cells.

The treatment has helped some children. It's still too soon to see any improvement in Emma, but the Jabs say without her banked cord blood there would have been no chance at all.

"You only have one opportunity to save the umbilical cord blood and I'm really happy that we did it," says Carrie Jabs.

"There really was no harm, no risk, It was her own blood being put back in, so absolutely I'm fully behind it," says Emma's father Michael.

But some doctors groups discourage private cord blood banking. The American Academy of Pediatrics says the chance that any one child would need it is so remote, that as an insurance policy, private cord blood banking is just too expensive.

Although associated with a private cord blood banking organization Children's Hospital Oakland Director of Research Dr. Bertram Lubin wrote the Academy of Pediatrics recommendations.

"The majority who have bank privately think the cord blood might be used, and it's not been used for a long period of time. It may never be used," says Dr. Lubin.

The recommendations encourage so-called public banking: donating cord blood for anyone's use. They also encourage banking cord blood to treat leukemia in a sibling. But the recommendations assert that private banking for healthy children makes no sense.

Multiply current estimates -- far fewer than one in 2000 children will ever need a stem cell transplant -- times the price to bank cord blood privately -- about $4,000: The result? You get a single experimental treatment effectively costing more than ten million dollars.

Admittedly, for one family it can be priceless.

"You don't know that you're not going to need it. In Emma's case, I banked it for Emma, and I needed it for Emma," says Carrie Jabs.

Michael Jabs made a similar argument. "People pay insurance on a car and never collect, so I'm willing to take that chance with insurance on the cord blood for my children and myself."

The Shermans are also thinking of their children. They consulted with nurse practitioner Barbara Dehn, who strongly favors private cord blood banking.

"It comes from my experience in the ICU, seeing a lot of children who unfortunately were waiting for those stem cell matches that never came," says Dehn.

Dehn explains there are payment plans and that stem cell therapies could work in siblings. But experts say personal stem cell therapies remain too far in the future.

"I'm firmly for public banking and sibling banking. For private banking, there isn't enough data research support to recommend that," says Dr. Lubin.

The Shermans expect their next child in about four months. They say they have not yet settled on cord blood banking. Doctors say they have right until the moment of delivery to make their decision.