Why the last weeks matter
In a January 2009 study coauthored by Dr. Thorp, more than 15 percent of newborns delivered by C-section at 37 weeks experienced at least one medical problem, compared with just 8 percent of 39-week babies. The researchers found that babies born at 37 weeks were four times more likely than 39-week infants to have breathing problems and about three times more likely to have low blood sugar, a severe bacterial infection, or a hospitalization lasting longer than five days. At 38 weeks, they were still about twice as likely to have one or more of those problems as a baby born a week later. But obvious health problems are just the tip of the iceberg, Dr. Thorp says. "Many early babies don't feed well, don't sleep well, and cause their families all sorts of heartaches," he explains. "It's subtle stuff that doesn't send you to the NICU, but it will impact the beginning of your child's life."
The risks are even higher for babies who arrive between 34 and 36 weeks. As a result, these babies, who once were called "near-term," are now known as "late preterm." Compared with a baby born at 37 weeks, they're four times more likely to have at least one medical condition, such as problems with body-temperature regulation, low blood sugar, respiratory distress, apnea, jaundice, and feeding difficulties, according to ACOG. While those problems may not linger long, researchers from the Centers for Disease Control and Prevention and the March of Dimes found that these infants are six times more likely to die in their first week and three times more likely to die in their first year of life than babies born after 37 weeks. "Fortunately, the overall risk of death is still very low," Dr. Thorp says.
Beyond the immediate medical problems, these deliveries may also be associated with learning disabilities, according to a recent study published in Pediatrics from the University of Florida. The researchers found that healthy late-preterm babies had a 36 percent higher risk of a developmental delay or disability in their first five years of life and were more likely to be held back in kindergarten than babies born after 37 weeks. And recent Stanford University research found that healthy late-preterm infants had lower reading scores through fifth grade and were more likely to need a special-education program in early elementary school than babies born closer to term. Happily, the sooner a child's learning problem is addressed, the more likely she will be able to catch up.