Cord blood and stem cells continue to flow to newborn in minutes after birth, review finds
WEDNESDAY, May 26 (HealthDay News) -- Pregnant women may want to consider asking their doctors to hold off on clamping the umbilical cord for a few minutes after the baby is born, a new study suggests.
Clamping the cord in the seconds after birth cuts off the blood flow from mom to baby. While not necessarily harmful, the common practice in delivery rooms potentially robs newborns of those last precious minutes of cord blood, the researchers said, and cord blood contains stem cells that have regenerative properties and can grow into different types of cells.
Research suggests there may be some benefits to getting that extra blood from mom right after birth, said senior study author Dr. Paul Sanberg, director of the University of South Florida's Center of Excellence for Aging and Brain Repair.
Delaying clamping for an extra minute or two may help prevent anemia in full-term infants, according to a study cited by the researchers. Studies on preterm infants have found delaying clamping the cord for 30 seconds or more reduced the incidence of anemia, intraventricular hemorrhage (brain bleeding), late-onset sepsis (a complication of infection in the days after birth), and decreased the need for blood transfusions, according to the study.
Calling the cord blood "nature's first stem cell transplant," Sanberg said more needs to be learned about the impact of cutting the cord before evolution intended.
"As we learn more about the value of cord blood, the benefits of delaying cord clamping may outweigh any risks, especially in preemies or in babies we know may have some problems before or shortly after birth," Sanberg said.
The paper, a review of medical literature on cord clamping, was published in a recent issue of the Journal of Cellular and Molecular Medicine.
In the womb, the umbilical cord connects the developing fetus to the mother's placenta. During birth, the placenta and umbilical cord contract and pump blood toward the newborn, according to background information in the article.
Within a few minutes of birth, the cord stops pulsing and blood flow ceases.
Evolutionarily speaking, women probably gave birth squatting, a position that would have helped the cord blood to rush toward the baby in the moments after birth, Sanberg said.
Birthing practices, of course, have changed for most U.S. women, and so have ideas about cord blood. Decades ago, doctors also believed the blood inside the cord was ordinary blood, Sanberg noted. Doctors now know umbilical cord blood contains stem cells.
"If you look at most historical societies, babies were born using gravity, which seems to help the transfer of the blood," Sanberg explained. "It's only in the last century that Western medicine has focused on clamping and cutting the cord to separate the baby so quickly."
Clamping cuts off blood supply prior to cutting the cord.
In the 1980s, ob-gyns were taught to clamp the umbilical cord of preterm infants quickly, said Dr. Bruce Young, a professor of obstetrics and gynecology at NYU Langone Medical Center.
Preterm infants are at higher risk of jaundice because they don't yet have a mature enough liver to break down bilirubin, a by-product of red blood cell metabolism. Preventing preterm infants from receiving that extra volume of blood from the mom was believed to help ward off jaundice, Young explained.
But as methods of caring for preemies improved, and doctors learned that exposing infants to light can help with bilirubin metabolism, early cord clamping was no longer encouraged, Young said.
In his experience, Young said, few doctors cut the cord in under a minute, even for full-term newborns. And many of today's moms request to have the baby placed on their abdomen before the cord is cut, further delaying cutting, Young said.
Still, the study brings up an interesting issue about what, if any, benefit another minute or so of cord blood might have for a baby.
"The standard of care is not to rush cord clamping," Young said. "My personal feeling is that the preponderance of evidence is that it's better to wait a minute or two."
A mother's decision to collect cord blood for storage and possible use later on could encourage early clamping to ensure there's plenty of blood to save. Experts urge moms not to hurry clamping for cord blood storage purposes.
Learn more about stems cells at the U.S. National Institutes of Health.
SOURCES: Paul Sanberg, M.D., director, Center of Excellence for Aging and Brain Repair, University of South Florida, Tampa, Fla.; Bruce K. Young, M.D., professor, obstetrics and gynecology, NYU Langone Medical Center, New York City; March 2010, Journal of Cellular and Molecular Medicine
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