Prospective parents face an array of medical decisions before their baby is born: Which pediatric practice to use? To circumcise, or not? What about prenatal testing to screen for possible genetic disorders?

In recent years a new question has arisen: Should they shell out $1,500 or more to store blood taken from their baby’s umbilical cord and placenta during delivery for possible personal use in the future? Cord blood contains stem cells that can be used in lifesaving transplants, often to treat blood cancers.

Since the mid-1990s more than two dozen private, for-profit cord-blood banks have sprung up in the United States, marketing this form of “just in case” insurance to new parents. Through targeted mailings and brochures displayed in obstetricians’ waiting rooms and hospitals, they seek to persuade new parents to pay for the collection and storage of cord blood that could prove valuable in treating a serious illness in the child or a close relative. In some states a parallel network of public banks allows parents to donate cord blood, which is typically discarded, for use free of charge by anyone who needs it, operating much as a conventional blood bank does.

So is private cord-blood banking a wise move for most parents?

Not according to a study published last month in the journal Pediatrics, which surveyed 93 pediatric transplant physicians in the United States and Canada. Its results echo reservations about the practice expressed by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. Last year ACOG called on its members to present balanced information about the pros and cons of the practice, to disclose potential conflicts of interest, and to tell patients it is not clear how long stored cord blood remains viable.

In the Pediatrics study, transplant specialists who collectively have performed thousands of stem cell transplants for childhood leukemia and other illnesses report that only 50 involved privately banked blood. (Support for public cord-blood banking is widespread in the medical community.) Forty-one cases involved blood used to treat a family member, often a sibling; in 36 of those cases the need for a transplant was known before the cord blood was collected. Only nine cases involved giving cord blood back to the donor, a practice known as autologous transplantation and the chief selling point for private cord-blood banking.

“In the absence of a family member known to be a candidate for stem cell transplant, the chances that privately banked cord blood will be used are quite small,” said Steven Joffe, co-author of the study and a transplant physician at Boston’s Dana-Farber Cancer Institute.

While stem cell transplants using infusions of cord blood can be lifesaving, they have limitations. In some cases cord blood cannot be used, because of the high probability that it contains malignant or otherwise damaged cells.

Montgomery County, Md., resident Frances Verter, founder of the Parent’s Guide to Cord Blood Foundation, called the Pediatrics study “ridiculous” and said it was a disservice to parents trying to make an important decision. Verter, whose oldest daughter died of leukemia in 1997 at age 4, said she privately banked the cord blood of her two younger daughters to avoid searching internationally in case one of them needed a future transplant. The blood remains in storage.

In Verter’s view, physician opposition to private cord-blood banking reflects an “entrenched mind-set” that could prove harmful to patients. “Suppose in a few years there are a lot of uses for cord blood?” she asked.

Cathy Pell fervently hopes that is the case. Pell, who lives in Manassas, Va., said she and her husband decided to spend $1,650 to bank the cord blood of her fifth child, Abby, in 2004 after watching talk show host Leeza Gibbons, who has been affiliated with a private cord-blood bank, extol its virtues on “Oprah.” They also pay about $100 annually in storage fees.

That cord blood has been used in the experimental treatment of Abby, now 4 1/2, who suffered severe brain damage after oxygen deprivation during delivery. The goal of the protocol, conducted at Duke University Medical Center, is to see whether infusions of stem cells can regenerate her damaged brain.

“I believe she’s better, but there’s no proof,” said Pell, whose daughter has undergone two treatments. “But I’m really glad we did it.”