As Babies Are Born Earlier, They Risk Problems Later

Such complications often require them to be sustained in the hospital for a week or two until they are fit to go home, adding thousands of dollars to the cost of their care. Often, they end up being readmitted once doctors realize they are not quite fully formed.

"These babies often masquerade as term babies," said Elizabeth A. Catlin of Massachusetts General Hospital in Boston. "They look like full-term babies -- they are chubby, they have a head of hair. But they just don't have the maturity and development of full-term babies."

In addition to the added cost and anxiety the complications cause, late-preterm babies are about five times as likely to die in the first week of life and about three times as likely to die in the first year than full-term babies, studies show.

"Doctors ought to be aware that there's no free lunch," said Michael Kramer of McGill University in Montreal. "There are a lot more babies out there who are getting sick and dying."

Although very little research has been done on these babies' long-term well-being, researchers suspect they may also be at increased risk for behavioral problems such as hyperactivity and possibly cerebral palsy and mental retardation.

"Could this group of babies be contributing significantly to the total burden of mental retardation in the United States and the world?" asked Gabriel J. Escobar of Kaiser Permanente Medical Care Program in Oakland, Calif. "I would say yes. We don't know how much, but it's not trivial."

Some studies have found evidence that these babies are more likely to have subtle problems with speech development and coordination and behavioral and learning difficulties.

"The thinking had been that these babies were basically the same as term babies," said Steven B. Morse of the University of Florida. "Now it looks like they really are different."

Morse presented a study at a conference in San Francisco this month that found late-preterm babies were significantly more likely to fall behind in reaching language, coordination and developmental benchmarks at age 3, were less likely to be ready to start preschool at age 4, and were more likely to need special-education classes, have behavioral problems and be held back in kindergarten.

"A lot of brain maturation occurs in those last few weeks," he said. "How the brain develops when the baby is still inside the mother may be different than how it develops when it is outside. If these kinds of development problems persist for these children, that is a concern from a societal standpoint."