Is 36 Weeks Preterm?
Yes, 36 weeks gestation is definitively considered preterm, as preterm birth is defined as delivery occurring before 37 completed weeks of gestation (before 37 0/7 weeks). 1
Definition and Classification
Preterm birth encompasses any delivery between 20 0/7 and 36 6/7 weeks of gestation, with term beginning at 37 0/7 weeks. 1
The late preterm period specifically includes gestations from 34 0/7 through 36 6/7 weeks, making 36 weeks squarely within the preterm classification. 1, 2
This classification is not arbitrary—it reflects meaningful physiological immaturity and increased risk for neonatal complications compared to term infants. 2
Clinical Significance of 36 Weeks
Infants born at 36 weeks face substantially higher risks than term infants, despite often appearing similar in size and weight:
Respiratory complications remain significant at 36 weeks, with respiratory distress syndrome rates of 3.2% compared to near-zero at term, though markedly improved from 15.0% at 34 weeks. 3
Other neonatal morbidities include hypothermia, hypoglycemia, feeding difficulties, jaundice, sepsis, and higher readmission rates after initial hospital discharge. 2
Hospital length of stay averages 4 days at 36 weeks versus minimal stays for term infants. 3
Management Implications
When delivery at 36 weeks is medically indicated, antenatal corticosteroids must be administered if not previously given, as the recommendation applies to all deliveries before 37 0/7 weeks. 1
For specific conditions requiring delivery at 36 weeks:
Intrahepatic cholestasis of pregnancy with bile acid levels ≥100 μmol/L warrants delivery at 36 0/7 weeks due to substantially increased stillbirth risk. 1, 4
Fetal growth restriction with absent or reversed end-diastolic velocity requires delivery between 30-34 weeks, making 36 weeks relatively late for these severe cases. 1
The ALPS trial established that corticosteroids benefit singleton pregnancies at 34 0/7 to 36 6/7 weeks when delivery is anticipated within 7 days, reducing respiratory support needs and severe respiratory morbidity. 1
Common Pitfalls to Avoid
Never treat 36-week infants as "near-term" or functionally mature—this outdated terminology led to inadequate care and underestimation of risks. 2
Do not assume that because an infant at 36 weeks appears term-sized, they have term-level physiological maturity—they remain physiologically immature with limited compensatory responses. 2
Avoid protocols designed for term infants when managing late preterm deliveries—these infants require heightened surveillance for temperature instability, feeding difficulties, hypoglycemia, and jaundice. 2
Do not withhold corticosteroids at 36 weeks if delivery is imminent and steroids have not been previously administered—the benefit extends through 36 6/7 weeks. 1