The need for a baby born at 37 weeks to enter the Neonatal Intensive Care Unit (NICU) is a common source of concern for expectant parents. While the majority of infants born at this stage are healthy and remain with their mother, a 37-week gestation carries a statistically higher chance of requiring specialized care compared to babies born a few weeks later. The NICU provides a controlled environment for newborns needing assistance with breathing, feeding, or maintaining a stable body temperature.
Understanding the 37 Week Classification
A pregnancy is generally considered full-term at 40 weeks, but medical organizations now use more specific classifications for the final weeks of gestation. An infant born between 37 weeks, 0 days and 38 weeks, 6 days is classified as “Early Term.” This is distinct from “Full Term,” which begins at 39 weeks, 0 days, and “Late Preterm,” which covers 34 weeks, 0 days through 36 weeks, 6 days.
The distinction is important because the last few weeks in the womb involve rapid, critical development for major organs. Although a 37-week baby may look fully developed, their lungs, brain, and liver have missed a final period of maturation experienced by infants born at 39 weeks. This slight developmental gap explains why early-term babies face a higher risk of certain complications and have an increased rate of NICU admissions compared to babies born later.
Specific Health Issues Leading to Admission
The primary reasons a 37-week infant is admitted to the NICU relate to the incomplete maturation of their organ systems. These infants are at increased risk for complications involving respiration, temperature stability, and nutritional competence. While many of these issues are temporary, they require the close monitoring and specialized interventions of the NICU or a special care nursery.
Respiratory Distress (TTN)
Respiratory distress, often manifesting as Transient Tachypnea of the Newborn (TTN), is a common reason for specialized care. TTN is caused by a delay in the clearance of fetal lung fluid after birth. The lungs of a 37-week infant may not have fully transitioned from a fluid-filled state to an air-filled state, which leads to rapid breathing (tachypnea) as the baby works harder to take in oxygen. This condition is usually short-lived, often resolving on its own within 24 to 72 hours. Infants may need supplemental oxygen and close observation until the fluid is fully absorbed.
Temperature Instability
Temperature instability, or difficulty with thermoregulation, is another frequent issue. Early-term infants have less subcutaneous fat than full-term babies, making it harder for them to generate and retain body heat. Their immature nervous systems also struggle to coordinate the body’s response to cold. These babies may need to be placed in an incubator or on a radiant warmer to maintain a safe, stable body temperature until they can regulate it independently.
Feeding Difficulties and Jaundice
Feeding difficulties and related jaundice are also common concerns for early-term babies. The coordination of the “suck-swallow-breathe” reflex requires a certain level of neurological maturity that may not be fully established at 37 weeks. Poor feeding can lead to inadequate weight gain and dehydration, which increases the likelihood of significant jaundice (hyperbilirubinemia). Jaundice occurs when the liver cannot efficiently process bilirubin, and if levels become too high, the infant may require phototherapy treatment in the NICU.
Discharge Criteria for Early Term Infants
Discharge from the NICU is based on the infant achieving a set of three physiological milestones, not a specific age or weight. Once a 37-week infant is admitted, the medical team focuses on helping the baby meet these criteria for a safe transition home.
The three primary discharge requirements are:
- Stable cardiorespiratory status. The baby must be breathing independently, maintaining a normal heart rate, and not experiencing significant episodes of apnea (pauses in breathing) or bradycardia (slow heart rate).
- Thermal stability. The infant must maintain a normal, consistent body temperature while fully clothed in a standard open crib. This demonstrates they no longer rely on an incubator or warmer to regulate heat. This period of stability is typically monitored for at least 24 hours.
- Nutritional competence. The baby must be successfully feeding by mouth, whether through breastfeeding or bottle-feeding, without needing a feeding tube. They must also demonstrate a consistent pattern of weight gain, ensuring they are taking in enough calories to thrive outside the hospital environment.
Most early-term infants who require NICU admission due to these issues have a short stay focused on stabilization, often lasting only a few days until these competencies are met.