The question of whether a baby is premature at 38 weeks often arises from a common misunderstanding of how medical professionals classify pregnancy timing. Historically, a wide five-week window was considered standard, leading to the belief that any delivery after 37 weeks was “term.” However, medical science shows that the final weeks of gestation are significantly different in terms of fetal development. Major health organizations now use precise categories to accurately reflect an infant’s health risks based on delivery timing.
How Gestational Age is Classified
A pregnancy is clinically defined as “Preterm” if delivery occurs before 37 weeks of completed gestation. Therefore, a delivery at 38 weeks is not considered premature by medical standards. Organizations like the American College of Obstetricians and Gynecologists (ACOG) have established specific gestational age designations for births occurring at or after 37 weeks.
A baby born at 38 weeks falls into the “Early Term” category, which covers 37 weeks, 0 days through 38 weeks, 6 days. The next category is “Full Term,” spanning 39 weeks, 0 days through 40 weeks, 6 days.
“Late Term” refers to delivery between 41 weeks, 0 days and 41 weeks, 6 days. “Post Term” is defined as any birth occurring at 42 weeks, 0 days or later. These classifications provide a standardized language for discussing the risks and outcomes associated with the timing of birth.
Specific Health Considerations at 38 Weeks
Although a 38-week infant is not premature, being born “Early Term” carries a measurable risk of temporary health issues compared to a baby born at 39 or 40 weeks. A common issue is transient tachypnea of the newborn (TTN), a temporary breathing difficulty. This often occurs because the lungs retain fluid that would typically be absorbed during a later delivery or cleared by the hormonal changes of labor.
Physiological Challenges
Infants born at 38 weeks also show an increased likelihood of difficulty with basic physiological functions outside the womb. These challenges include coordinating the complex actions of sucking, swallowing, and breathing necessary for successful feeding. Maintaining a stable body temperature, known as thermoregulation, can also be more difficult for these newborns.
Metabolic Complications
Early Term babies face higher rates of metabolic complications in their first days of life. These include neonatal jaundice, which may require phototherapy, and hypoglycemia, or dangerously low blood sugar. Research shows these infants are more likely to require admission to the neonatal intensive care unit (NICU) than their Full Term counterparts.
The Rationale Behind Current Term Definitions
The current, granular classification system was implemented because medical data showed that health outcomes were not uniform across the historical “term” window of 37 to 42 weeks. Previously, the medical community treated all deliveries in this range as having similar prognoses, but this generalized view masked important differences. Research revealed that babies born at 37 and 38 weeks had statistically higher rates of short-term morbidity than those born at 39 weeks or later.
The “Early Term” designation was established to acknowledge this increased risk. By creating distinct categories, medical bodies could discourage non-medically indicated deliveries before 39 weeks of gestation. This shift helps clinicians and parents recognize that while a baby is not premature at 38 weeks, the final weeks of pregnancy provide significant developmental benefits, particularly for the brain and lungs.