The Early Show medical correspondent Dr. Emily Senay says low birth weight affects about 1 in every 13 babies born each year in the United States. It can occur when a baby is born prematurely or doesn't grow to a normal weight during pregnancy.
During the newborn period, low birth-weight babies are at immediate risk of serious health woes, including breathing problems and bleeding in the brain, Senay explains. Babies with low birth weights may be hospitalized in neonatal intensive care for monitoring and treatment.
The good news for these babies is that advances in medical science and technology during the 1990s have dramatically increased their chances of survival, even among those with extremely low birth weight.
A study published in Wednesday's Journal of the American Medical Association indicates that 70 percent of the almost 23,000 babies born in the U.S. in 2002 weighing between 1.1 and 2.2 pounds survived.
But the study finds that they faced other problems once they leave the hospital.
The study looked at more than 200 children with extremely low birth weights (under 2.2 pounds) and found higher rates of chronic physical and mental problems than those experienced by children of normal birth weight.
By the time they were 8 years old, the extremely low birth-weight babies had higher rates of cerebral palsy, asthma and visual disability, as well as poorer cognitive ability, academic achievement, motor skills and social adaptive functioning.
Children born during the same years with normal weights were two or three times less likely to suffer from the same problems.
It's very important to monitor children born at extremely low birth weights as they grow older, to spot any health or developmental problems as early as possible, Senay points out. There are effective treatments, therapies and other interventions for many of these conditions. Those treatments can really help these kids along the way. It's important to identify problems so children can get the care they need as soon as possible.
We don't fully understand the reasons for low birth weight and premature birth, and there's no known cause for more than half of premature births, Senay adds. But women of childbearing age should seek advice from their doctors and be aware of the known risk factors for low birth weight, such as multiple births, high blood pressure, diabetes, and lifestyle factors including drinking and smoking.