Primarily to improve delivery outcomes, obstetricians and gynecologists have redefined ‘term pregnancy.’ By joint action, the American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) have discarded the label ‘term pregnancy’ and replaced it with four more specific tags: ‘early term,’ ‘full term,’ ‘late term,’ and ‘postterm.’
“Each week of gestation up to 39 weeks is important for a fetus to fully develop before delivery and have a healthy start,” Jeffrey L. Ecker, M.D., chair of ACOG’s Committee on Obstetric Practice, stated in a press release. “This terminology change makes it clear to both patients and doctors that newborn outcomes are not uniform even after 37 weeks.”
Date of Delivery
A pregnancy with a single fetus lasts, on average, 40 weeks from the first day of the last menstrual period. In fact, this is the standard calculation used by ob/gyns to determine an estimated date of delivery (EDD). Until now, the ob/gyn community considered babies born anytime between three weeks before the EDD and two weeks after the EDD (37–42 weeks of gestation) as ‘term.’
“Doctors believed that babies delivered in this five-week window had essentially the same good health outcomes,” Ecker stated in a press release.
However, recent research has proved such beliefs false. Every week of gestation matters for the health of newborns. For instance, the last few weeks within the full-term 40 week period permit a baby’s brain and lungs to fully mature. Compared with babies born earlier or later, babies born between 39 weeks and 40 weeks plus six days gestation have the best health outcomes so it has been renamed “full term,” as indicated in the chart of newly-defined term periods below:
- Early Term: Between 37 weeks 0 days and 38 weeks 6 days
- Full Term: Between 39 weeks 0 days and 40 weeks 6 days
- Late Term: Between 41 weeks 0 days and 41 weeks 6 days
- Postterm: Between 42 weeks 0 days and beyond
With their announcement of new labels, ACOG and SMFM have begun to encourage physicians to adopt these terms as a way of providing the highest quality pregnancy care. The two organizations also hope the new labels will improve researchers' ability to collect precise data on newborn health. Additionally, these new labels clarify the organizations' recommendation that planned deliveries before 39 weeks should occur only when significant health risks are posed by continuing the pregnancy.
Although delivery before 39 weeks 0 days may in some cases be unavoidable, such as when a woman’s water breaks early or contractions begin well before her EDD, any version of a non-medically indicated early-term delivery should be avoided. Over the past few decades, rates of elective induction — a medical procedure is used to ‘trigger’ contractions prior to the beginning of the natural process of labor — rose steeply, increasing from just 9.5 percent in 1990 to 22.1 percent in 2004. Reasons for such early deliveries include prior bad pregnancies, convenience, work/schedule conflicts, and distance, as when a woman lives far from a hospital.
Only very recently, the past two years or so, the trend among ob/gyns has been to discourage elective induction due to the potential for complications and health issues among neonatal babies.
“The differences between 37 weeks of gestation and 39 weeks of gestation are consistent, larger, and statistically significant across multiple studies,” ACOG stated in a Committee Opinion report published in April. “Even comparing neonates and infants delivered at 38 weeks of gestation with those delivered at 39 weeks of gestation there is still an increased (albeit clinically small) risk of adverse outcomes.”
ACOG describes itself as a private, voluntary organization of approximately 57,000 members that advocates for quality health care for women, while increasing awareness of the changing issues facing women’s health care.