A baby born at 35 weeks of gestation is classified as a late preterm infant, defined as a birth occurring between 34 0/7 weeks and 36 6/7 weeks. While these babies often look similar to full-term infants, their organ systems are physiologically immature, requiring specialized monitoring immediately after birth. This immaturity necessitates a longer period of observation and stabilization in the hospital compared to a full-term baby. The duration of the stay is determined by the baby’s ability to meet specific functional milestones, not a fixed calendar date.
The Late Preterm Designation
Though a 35-week infant is close to term, they missed a critical period of development, especially for the brain. This immaturity translates into a higher risk for several common medical challenges. For example, the coordination required for the suck, swallow, and breathe sequence during feeding is often underdeveloped, leading to insufficient calorie intake and weight loss.
Late preterm babies possess less body fat and have an immature central nervous system, making it difficult to maintain a stable body temperature (thermoregulation instability). The less mature liver increases the likelihood of hyperbilirubinemia, which manifests as jaundice and may require phototherapy. These babies are also at a higher risk for hypoglycemia, or low blood sugar, due to fewer stored glucose reserves and difficulty coordinating feeds.
Typical Duration and Location of Stay
The typical hospital stay for a baby born at 35 weeks is variable, often falling within a range of five to 14 days. The exact duration depends entirely on the resolution of initial medical issues and the time it takes for the infant to demonstrate physiological maturity. Immediately after birth, a 35-week baby is commonly monitored in a Special Care Nursery (SCN) or a Level II Neonatal Intensive Care Unit (NICU).
This setting allows for continuous monitoring of vital signs, blood sugar, and bilirubin levels, which is critical in the first few days of life. The facility provides an environment where staff can quickly address common late preterm complications like respiratory distress or temperature instability. For infants requiring more involved care, such as assistance with breathing or intravenous fluids, the stay extends until they are stable enough to transition to less intensive observation.
Milestones Required for Discharge
Discharge for a late preterm infant depends on the consistent achievement of functional developmental goals, not simply reaching a certain chronological age. The three primary physiological milestones that must be met are sustained feeding, stable thermoregulation, and respiratory stability, typically demonstrated consistently over a 24- to 48-hour period.
The feeding milestone requires the baby to take all nutrition orally, without the need for a feeding tube. The infant must demonstrate the ability to coordinate sucking, swallowing, and breathing to consume enough to gain weight or promptly regain their birth weight. Since late preterm infants tire easily during feeds, the healthcare team closely monitors their feeding efficiency and overall intake to ensure adequate nutrition.
Thermoregulation stability means the baby can maintain a normal body temperature in an open crib, dressed in regular clothing, rather than requiring an incubator or radiant warmer. This transition indicates the baby’s internal systems are regulating heat effectively. The respiratory milestone involves the baby maintaining stable breathing without experiencing episodes of apnea (a pause in breathing) or bradycardia (a low heart rate).
Before discharge, the baby must pass a car seat challenge test to ensure breathing and heart rate remain stable while seated. This test is important because the semi-reclined position can sometimes compromise the airway of a late preterm infant. Additionally, all mandatory newborn screenings, such as hearing and metabolic screenings, must be completed. Any hyperbilirubinemia must also be resolved or managed with a clear outpatient plan.
Transitioning Home and Follow-up Care
Once the physiological milestones are met, the transition home requires careful planning and coordination with the family and outpatient providers. Due to the heightened risks associated with late preterm birth, a follow-up appointment with a pediatrician is often scheduled within 24 to 48 hours of discharge. This early visit is crucial for monitoring weight gain and checking for the potential rebound of jaundice, as bilirubin levels can peak after the hospital stay.
Parents receive specific guidance on monitoring their infant’s temperature, feeding patterns, and alertness, including clear instructions on when to seek medical attention. Due to immature immune systems, late preterm infants are susceptible to infections and may be candidates for Respiratory Syncytial Virus (RSV) prophylaxis, a seasonal injection. Ongoing monitoring of growth and development is important, and pediatricians often use the infant’s corrected age (based on the original due date) for developmental screenings in the first few years of life.