What is the gestation cutoff for term?

Gestational Age Cutoff for Term Pregnancy

Term pregnancy begins at 37 weeks 0 days of gestation, but this designation has been refined into subcategories to reflect important differences in neonatal outcomes throughout the 37-42 week period. 1

Current Term Pregnancy Definitions

The American College of Obstetricians and Gynecologists (ACOG) replaced the single label "term" with four distinct designations to more accurately reflect varying 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
• 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 Rationale for Refined Definitions

The traditional 5-week "term" window (37-42 weeks) was determined somewhat arbitrarily and assumed uniform neonatal outcomes, which research has proven incorrect 2:

• Early term births (37-38 weeks) carry increased risks compared to full term births, including higher rates of respiratory morbidity, neonatal mortality, lower birth weights, precipitous labor, birth injury, and need for ventilation 1, 2, 3
• Neonatal outcomes improve progressively from 37 weeks through 39-40 weeks of gestation 1, 2
• The designation "term" carries significant clinical implications for timing of both elective and indicated deliveries 2

Clinical Application

Elective deliveries should not occur before 39 0/7 weeks of gestation in low-risk pregnancies 4:

• NICE guidelines specifically define term as 37-41 weeks' gestation for intrapartum care of healthy women 4
• ACOG recommends considering elective induction in low-risk nulliparous women starting at 39 0/7 weeks of gestation, not earlier 4
• Early term neonates (37-38 weeks) have increased risk of respiratory morbidity, making elective delivery at <39 weeks inadvisable 4

Accurate gestational age dating is essential to avoid iatrogenic early term or preterm delivery 4:

• Dating should be confirmed by early ultrasonography 4
• For certain last menstrual period, ultrasonography confirmation should occur at <21 weeks 4
• For uncertain last menstrual period, only first-trimester ultrasound dating should be used 4

Management Beyond Full Term

• Induction of labor should be offered by 42 0/7 weeks to reduce risks of stillbirth, perinatal mortality, and cesarean delivery 5, 6
• Antepartum monitoring should begin at 41 0/7 weeks of gestation 5
• Stillbirth risk increases from 39 weeks onwards with a sharp rise after 40 weeks 6