ACOG/SMFM: Replace Phrase 'Term Pregnancy' With 4 Categories

Marcia Frellick

October 22, 2013

Using the general phrase "term pregnancy" to refer to births between 3 weeks before the estimated date of delivery and 2 weeks after does not convey the distinction of health benefits and risks for each week of gestation in that window, according to the nation's obstetricians and gynecologists.

The American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) wrote a joint opinion published in the November issue of Obstetrics & Gynecology discouraging use of the general label "term pregnancy" and replacing it with these categories:

  • early term: 37 weeks to 38 weeks, 6 days;

  • full term: 39 weeks to 40 weeks, 6 days;

  • late term: 41 weeks to 41 weeks, 6 days; and

  • post-term: 42 weeks and beyond.

"Until recently, doctors believed that babies delivered in this 5-week window had essentially the same good health outcomes," Jeffrey L. Ecker, MD, chair of the college's Committee on Obstetric Practice, said in a news release. "This terminology change makes it clear to both patients and doctors that newborn outcomes are not uniform even after 37 weeks."

The committee noted in the opinion that outcomes are best for delivery at "full term" (39 weeks - 40 weeks, 6 days). ACOG and SMFM are encouraging physicians, researchers, and public health officials to adopt the new terms to improve data collection and reporting and clinical research, as well as provide the highest-quality pregnancy care.

Peter Bernstein, MD, MPH, obstetrician/gynecologist and maternal-fetal medicine specialist at Montefiore Medical Center in New York City, said the committee's recommendations will formalize a push in the medical community in the last few years to stop scheduling elective deliveries before 39 weeks, a practice that had become more common as families and physicians set the dates for convenience.

"Literature has become very clear that babies born at 37 weeks don't do as well as babies born at 38 weeks, and babies born at 38 weeks don't seem to do as well as those born at 39 weeks, so this arbitrary line saying a baby born at 37 weeks is full-term has led to this normalization of deviance," Dr. Bernstein told Medscape Medical News.

He said it is also important to note that babies thought to be 37 weeks may actually be misdated and at even more risk, at a younger stage of gestation.

Although sometimes delivery before 39 weeks is unavoidable, planned deliveries before 39 weeks should occur only when there are significant health risks to a woman and/or the fetus in continuing the pregnancy, Dr. Ecker said in the news release.

That view is reflected in a related committee opinion, published in April. In that statement, the committee emphasized that the risk for adverse outcomes is greater for neonates delivered in the early-term period compared with those delivered at 39 weeks.

Mortality rates are also higher among neonates and infants delivered in the early term compared with full-term births.

For example, a study published in September also found that compared with term infants born from 39 to 41 weeks' gestation, early-term infants born between 37 and 38 weeks' gestation had a 7-fold higher risk for neonatal morbidity and were at greater risk for admission to the neonatal intensive care unit or neonatology service.

Dr. Bernstein said the committee's latest recommendations will add weight to the push against electing to deliver before 39 weeks without a medical reason.

"I think it's a really good thing. This is something that's been gathering steam," he said.

Obstet Gynecol. 2013;122:1139-1140.


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