pregnant womensSome 8,000 mothers who give birth at Brigham and Women’s Hospital each year can now donate blood from their umbilical cords to a public bank where it may be a match for someone facing a life-threatening disease.

Public banks, which store cord blood for the stem cells that can combat leukemia, lymphoma, and other deadly illnesses, have existed for two decades, yet they have been eclipsed in recent years by private banks that urge mothers to pay an annual fee to bank the cord blood, in case their child or a relative needs it one day.

The Brigham and Women’s donation center, which opened in late May, is the first in Boston and has so far collected 130 cord-blood donations. Two other hospitals in New England allow mothers to donate cord blood - UMass Memorial Medical Center in Worcester and Women & Infants Hospital in Providence.

Demand for the opportunity to donate cord blood was strong among Boston women, said Dr. Robert Barbieri, chairman of obstetrics and gynecology at Brigham and Women’s and co-coordinator of the program. Barbieri said he received several calls each month from women asking where they could donate.

“It’s a great way to use a biological resource to give people hope for the future,’’ said Barbieri. “It’s a gift of life.’’

Pregnant women interested in donating cord blood fill out a medical history and consent form. After delivery, their blood is tested for diseases, and the stem cells are separated and mailed to the Carolinas Cord Blood Bank at Duke University, which helped train nurses and technicians at Brigham and Women’s. Now, only women delivering babies during daytime hours - when the technicians are on call - are able to donate cord blood.

Supporters of public cord-blood banks - including the American Academy of Pediatrics and the National Marrow Donor Program - want to inform the public that in families with healthy medical histories, donating cord blood to a private bank can be a waste of both money and an important biological resource that is more likely to be used if donated rather than stored in a family bank.

In patients with diseases that affect blood or bone marrow, a cord-blood transplant can be a lifesaver. The blood is rich with stem cells, which are essential in forming new, healthy blood. In patients with diseases such as leukemia, stem cells malfunction and must be destroyed with radiation or chemotherapy. Bone marrow transplantation replaces and restores those cells.

“In the transplant community, we recognize that nationally there is a shortage of compatible donors,’’ said Dr. Joseph Antin, chief of the stem cell transplant program at Dana-Farber Cancer Institute, and co-coordinator of the donation program. “The most important thing for me when I have someone who needs a transplantation is that they find a donor,’’ said Antin.

However, the likelihood of finding a good donor largely depends on how many siblings the patient has. For a family with two children - the average size of American families - the patient has a 25 percent chance a brother or sister will be a match. If a family match cannot be determined, physicians look to the National Marrow Donor Registry, said Antin.

There, potential donors need to be a very close match, or have marrow with a similar protein structure, to avoid complications in the transplant. About 70 percent of Caucasian and 50 percent of African-American cancer patients can find a blood marrow donor through their families or the registry, said Antin.

Yet many others can’t - and that is where cord blood comes in.

Because babies have not been exposed to viruses, their cord blood is “immature,’’ or more of a blank canvas than adult bone marrow, so a less-precise match can still be successful. It is also available to transplant patients within days of being collected. With bone marrow, if a match is made, the donor has to be tracked down for his or her marrow to be extracted, which can take days or weeks.

“For people who don’t have a lot of genetic relatives in this country, cord blood offers a very popular option,’’ said Barbieri.

At UMass Memorial, private banks are not allowed to advertise in the hospital, said Dr. Mary Herlihy, chief of general obstetrics and gynecology and coordinator of the center’s cord-blood donation program. Once patients are informed about public banking, most want to go that route, she said.

“The problem with public banking at the moment is that the opportunities are so limited,’’ she said.

Barbieri hopes that will change as more women learn about public banking.