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What Does 'Full-Term' Baby Mean, Anyway?

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In recent years, when obstetricians have recommended, and women have requested, non-emergency C-sections, the guidelines for scheduling surgery allowed for birth as early as 37 weeks. Facing a growing body of research showing that babies born this early often face higher health and development risks, the American College of Obstetricians and Gynecologists voted recently to move the goal posts by a couple of weeks and change the definition of "full-term."

ACOG now defines babies born between 37 and 39 weeks as "pre-term." Only those who make it to the 39+ mark get the full-term stamp.

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You'd think the medical community would have birth all figured out by now, but, in reality, obstetrics is still evolving, which is apparent in the professional organization's actions. The change, the organization says, recognizes the fetal growth and development up to and including the very last weeks in utero. Babies born between 39 and 41 weeks do best, members of ACOG argue.

ACOG's actions are an effort to standardize best practices, too. A study in 2009 in the journal Obstetrics & Gynecology found confusion in the medical community about what defined a full-term birth. ACOG attributed this confusion to the continued rise in the number of elective births at the very early edge of viability. "When asked when a pregnancy reached "full-term," 24 percent said 34 to 36 weeks, 51 percent said 37 38 weeks and just 25 percent said 39 to 40 weeks."

Your doctor might encourage you to stay pregnant for a couple of weeks longer than you had hoped.

Doctors have been green-lighting these 37- and 38-week births because, for the most part, 37- and 38-week babies did pretty well. That hasn't changed. But what ACOG says is clear is that babies born at 39 weeks or later did even better.

The organization cited increased risks, as well, for those fetuses who like to linger in-utero when it narrowed the definition of normal in the post-40-week pregnancies. Whereas it used to be that births after 42 weeks gestation were considered full-term, any baby born after 40 weeks and six days is considered "late-term." From 42 weeks and on, the baby is labeled "post-term."

Until now, most baby books defined normal pregnancy between 38 and 42 weeks.

The new definitions are as follows:

  • Early-term: Between 37 weeks 0 days and 38 weeks, six days
  • Full-term: Between 39 weeks and 40 weeks, six days
  • Late-term: Between 41 weeks and 41 weeks, six days
  • Post-term: 42 weeks and beyond

So what does this mean for pregnant women? That depends on how closely your OB follows ACOG recommendations. Your doctor might encourage you to stay pregnant for a couple of weeks longer than you had hoped. Or, you might be recommended for an induction, even if your other babies tended to toe that 42-week line.

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Dr. Claudia Gold, who blogs for the Boston Globe at Child Mind, welcomes the new definitions, particularly the "early term" classification. In the past, she argues, babies born at 37 weeks were cared for right alongside those who made it to 40 weeks and beyond, receiving no specialized support. These earlier babies may have struggled with nursing—not because they couldn't or mom couldn't, but because they still needed a bit of time to develop. Recognizing they may have special needs, she argues, could have helped not only the baby but the mother as well.

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