Late preterm, in contrast, reflects the chillier conclusions of recent research and recommendations: Babies should not be delivered before 39 weeks unless there is a compelling medical reason because they are physically immature.
Even though they often look reassuringly sturdy, they have trouble with such basics as feeding, staying warm, breathing, and what is unscientifically called "filling a diaper." As a result, they are far more likely to have to stay in the hospital - and to be readmitted after they go home - than full-term babies.
Indeed, a large new study of 19,000 late preterm newborns found that 37 percent had to be admitted to the intensive care nursery, in many cases because of breathing difficulties. At 34 weeks, the odds of respiratory distress were 40 times higher than at 39 weeks, according to the research, published last week in the Journal of the American Medical Association.
Briana Pray and Terren Jackson were braced for respiratory problems when their firstborn made his debut by cesarean section at 33 weeks.
"The pediatrician warned us that because his lungs are immature, he might need to be put on a breathing machine," Pray recalled last week as Terren nestled in his father's arms. "Fortunately, he came out breathing."
Even so, it wasn't until Friday, after 15 days in the intensive care nursery, that the five-pound Terren went home to West Philadelphia.
Federal statistics show that the rate of premature birth has soared 30 percent since 1980. About 13 percent of births are now before 37 weeks, for reasons that are not well-understood.
In the public mind, the word premature conjures images of a fragile, skeletal, palm-size preemie in an incubator, hooked to a welter of life-supporting machines.
