When deciding whether to bank your baby’s umbilical cord blood, consider these caveats

Umbilical cords tie mother and baby together, if only for a brief spell. But the stuff inside these cords has the potential to be useful well after birth. Cells in umbilical cord blood are already being used to treat certain diseases, including leukemia and rare forms of anemia. But for all the excitement about umbilical cord cells, in many ways, this research is still in its infancy.

Parents who are optimistic about that research future and want to save these cells have two options in the United States: Public not-for-profit cord banks and private cord banks. Here, about 30 public banks rely on donations from mothers, who don’t have to pay for the donation. After delivery, blood from the umbilical cord and placenta is collected, checked for quality, entered into a registry and then put in a deep freeze. And like the blood that’s collected in blood drives, these cells become available to anyone who might need them — not just the family that donated them.

There is currently no shortage of willing donors. I was willing, but I wasn’t able to find a participating hospital and cord blood bank that could take my samples after my daughters’ births. “Public banks are not a moneymaking endeavor,” says Joanne Kurtzberg of Duke University, who helps run a public cord bank in North Carolina. As such, these banks have limited resources and can’t afford to take, test and store every possible sample. Kurtzberg estimates it costs public banks between $3,000 and $5,000 to collect a single unit.

These public banks fulfill an important need, but they fly under the radar of many parents. More likely, parents will have encountered marketing messages from private banks. These banks are more easily accessed, but at a cost. Billing themselves as providing a “potentially healing resource for your family’s future,” for example, private banks mail parents-to-be cord blood collection kits to have on hand during delivery, and then store umbilical cord blood samples for exclusive use by the donating family, should a family member ever need it. The fees vary, but they can be several thousand dollars for collection, plus indefinite annual maintenance fees.

Both types of banks may make special accommodations for families who have a member likely to benefit from a cord blood transplant. Public banks will accept a sample earmarked for a family with a child at high risk of leukemia or lymphoma, for instance. Similarly, some private banks offer breaks for families with a member with a disease that can be treated with such a transplant. Scientists estimate that, worldwide, there are nearly 800,000 cord blood samples in public banks, and more than 5 million stored in private banks.

There are plenty of science-based caveats when it comes to cord banking, and you might not find them in the brochures of private cord banks. For starters, in the majority of transplants that have been performed, cord blood has not been used on the child who donated the blood. In many cases, a patient’s own cells are considered unsafe. Umbilical cord cells from a child who develops leukemia are more likely to develop leukemia themselves, prompting physicians to steer clear of these cells. And for genetic diseases, the same genetic trouble would be present in the umbilical cord stem cells as in the child’s body cells.

Another issue concerns cell quality. For a transplant to work, there must be enough high-quality cells — and no bacteria or other harmful agents — in the sample. In not-for-profit public banks, scientists estimate that only about 25 to 40 percent of the samples meet the stringent quality criteria needed for transplants.

The quality of blood products is even lower in private banks, research has suggested, perhaps because they’re not necessarily subjected to the same regulatory oversight as the public banks. Unlike public banks, private banks aren’t required to get rid of samples that don’t meet quality standards. The quality of products might vary drastically from bank to bank. Only 18 percent of samples were stored frozen in liquid nitrogen, a common practice used in public banks, one study found. And bacteria were present in 7.6 percent of samples from private banks, but only 0.5 percent of samples from public banks. “The quality of the public cord blood banks is far stricter and better than the private system,” says pediatrician William Shearer of Baylor College of Medicine and Texas Children’s Hospital.

The volume of cells saved is key. As anyone who’s ever seen a fresh baby knows, they’re tiny. The amount of blood that can be milked from an umbilical cord is not huge. That can be a problem, especially for older kids or adults who might need transplants. According to one estimate, only 8 to 12 percent of umbilical cord samples have enough cells for a transplant to an adult weighing about 176 pounds. And the recent trend toward delayed cord clamping during birth, which allows more time for the umbilical cord blood to get into the baby, might further reduce harvested cells.

All told, cord blood stored in public banks have 30 times the likelihood of being tapped for a transplant as samples stored in private banks, researchers have estimated. Cells stored in public banks are “more likely to be used,” Kurtzberg says, “and there are lots of patients out there who need it.”

So it’s clear that these cells are not a miracle cure for everything that might afflict a child, nor are they necessarily high-enough quality to be used. For some disorders, donor cells may work just as well as (or better than) a person’s own cells. In an ongoing trial of umbilical cord infusions’ effects on autism symptoms, Kurtzberg and her colleagues are comparing the effects of children’s own cells and donor cells.

All the considerations can leave parents deciding whether to bank anxious and uncertain. In my next post, I’ll dig into some recommendations and offer ways to think about the issue.