Definition of Full-Term Delivery
Full-term delivery is defined as birth occurring between 39 0/7 weeks and 40 6/7 weeks of gestation, while the broader term "term delivery" encompasses early term (37 0/7 to 38 6/7 weeks), full term (39 0/7 to 40 6/7 weeks), late term (41 0/7 to 41 6/7 weeks), and postterm (≥42 0/7 weeks). 1
Gestational Age Classifications
The American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine replaced the outdated single designation of "term" with four distinct categories to reflect significant differences in neonatal outcomes 1:
- Early term: 37 0/7 weeks through 38 6/7 weeks of gestation 1
- Full term: 39 0/7 weeks through 40 6/7 weeks of gestation 1, 2
- Late term: 41 0/7 weeks through 41 6/7 weeks of gestation 1
- Postterm: 42 0/7 weeks of gestation and beyond 1
Clinical Significance of the Distinction
The designation "full term" specifically refers to the optimal window for delivery (39-40 6/7 weeks) when neonatal outcomes are best, whereas "term" is a broader umbrella term that includes all deliveries from 37 weeks onward. 1
Why This Matters for Outcomes
- Respiratory morbidity varies significantly across the 37-42 week gestational age range, with early term infants experiencing higher rates than full-term infants 1, 3
- Neonatal mortality increases at both ends of the spectrum: infants born at 37-38 weeks have higher mortality than those born at 39-40 weeks, and mortality rises again after 41 weeks 3, 4
- Contemporary research demonstrates improved outcomes with delivery during the full-term period (39-40 6/7 weeks) compared with the early term period (37-38 6/7 weeks) 2
Historical Context
The previous definition of "term" (37-42 weeks) was determined somewhat arbitrarily and incorrectly assumed uniform neonatal outcomes across this 5-week interval 3. The growing body of evidence showing significant outcome differences led to the 2013 reclassification 1.
Clinical Application
- Nonindicated elective deliveries should not occur before 39 0/7 weeks to optimize neonatal outcomes 2, 1
- Medical, obstetric, and fetal indications may necessitate delivery before 39 weeks, requiring careful risk-benefit analysis 2
- The uniform use of these specific gestational age designations is endorsed by ACOG and SMFM for clinical practice, research, and public health reporting 1
Common Pitfall to Avoid
Do not use the outdated term "term pregnancy" to refer to all deliveries from 37-42 weeks without specifying the subcategory, as this obscures clinically important differences in neonatal risk 1, 3. Always specify whether delivery is early term, full term, late term, or postterm 1.