A baby born at 35 weeks gestation is considered “late preterm.” This classification applies to infants born between 34 weeks and 0 days and 36 weeks and 6 days of gestation. The term “late preterm” replaced the older phrase “near term” to emphasize that these infants, while close to full-term, are not yet fully mature. Their physiological and metabolic systems are still developing, making them more vulnerable than babies born at full term.
Understanding 35 Weeks Gestation
By 35 weeks, a baby typically measures around 17 to 18 inches (43.2 to 46.3 centimeters) from head to heel. Their weight usually falls within the range of 5.25 to 6 pounds (2.4 to 2.7 kilograms). Babies at this stage continue to gain weight, often adding about half a pound to a pound each week until birth.
Significant development occurs during this period, particularly with fat accumulation around the shoulders, which is important for maintaining body temperature after birth. While a baby’s lungs are nearly developed, full maturity typically occurs closer to 36 to 40 weeks. Adequate surfactant, a substance that helps keep air sacs open, is usually present by 35 weeks to support breathing, though some babies may still require assistance.
The brain continues its rapid growth, weighing approximately two-thirds of what it will at 39 to 40 weeks. The baby’s kidneys are fully developed, and the liver begins processing waste products. The intestinal system also matures, preparing for nutrient intake after birth.
Common Health Considerations
Babies born at 35 weeks often face specific health challenges due to their physiological immaturity. Respiratory distress is a common concern, as their lungs may not be fully mature. This can manifest as Respiratory Distress Syndrome from insufficient surfactant, or Transient Tachypnea of the Newborn due to fluid retention. Up to 8% of babies born between 34 and 36 weeks may experience breathing difficulties.
Feeding can also present difficulties for late preterm infants. Their coordination of sucking, swallowing, and breathing is still developing, making efficient feeding challenging. Babies may tire easily, not provide clear hunger cues, or struggle to transfer milk effectively. Approximately 42% of babies born at 35 weeks may experience feeding issues.
Temperature instability is another consideration, as these infants have less body fat and an immature ability to regulate their temperature. This makes them prone to hypothermia, which can increase the risk of other health complications. Close monitoring and external warming support are often necessary.
Jaundice, characterized by yellowing of the skin and eyes, is prevalent due to the baby’s immature liver struggling to process bilirubin. This condition can sometimes necessitate medical intervention. Late preterm babies are also at an increased risk of low blood sugar (hypoglycemia) due to limited glycogen and fat stores and immature metabolic regulation. These blood sugar fluctuations require careful monitoring. These issues often lead to a higher rate of hospital readmission for late preterm infants.
Medical Care and Support After Birth
Babies born at 35 weeks gestation often require specialized medical care and close observation after birth. Many will spend time in a Neonatal Intensive Care Unit (NICU) or a special care nursery to ensure their stability and support their development. This environment allows continuous monitoring of vital signs, including heart rate, respiratory rate, oxygen saturation, and temperature.
Maintaining a stable body temperature is a primary focus; infants may be placed in an incubator or under a radiant warmer. Skin-to-skin contact, also known as Kangaroo Care, is highly encouraged. This practice supports thermal regulation and fosters bonding, while also promoting stable heart rates, breathing patterns, and improved sleep for the infant.
Feeding support is often necessary due to immature suck-swallow-breathe coordination. Some babies may initially receive nutrition through gavage feeding. Breast milk is the preferred nourishment, and mothers are encouraged to pump if direct breastfeeding is not yet possible. As the baby matures, they transition to oral feeds, potentially using specialized bottles or fortified milk to ensure adequate nutrition.
Discharge from the hospital is typically considered when the baby can consistently maintain their body temperature in an open crib, feed adequately by mouth to support healthy growth, and demonstrate stable breathing. For uncomplicated late preterm infants, the average postmenstrual age at discharge is around 36 weeks.
Outlook for 35-Week Babies
The long-term outlook for babies born at 35 weeks is generally positive, with most thriving and catching up developmentally. Many late preterm infants experience “catch-up growth,” accelerating their weight and length gain to align with full-term peers, often within the first two to three years of life. While some may remain slightly smaller, individual genetics also contribute to a child’s eventual size.
Despite a generally favorable prognosis, there is a slightly increased risk for certain neurodevelopmental differences compared to full-term babies. These can include mild delays in motor milestones, speech and language development, or attention. However, research findings on the persistence of these differences can be inconsistent, with some studies indicating complete catch-up in development. Some evidence suggests a potential for increased risk of certain health conditions later in life, such as high blood pressure, metabolic differences, or mental health considerations. Regular follow-up with healthcare providers is recommended to monitor growth and development, allowing for early identification and intervention.