Newborn Adaptation to Extrauterine Life

• The adaptation of a newborn to extrauterine life involves significant physiological and behavioral changes
• These changes occur as the newborn transitions from dependence on the maternal-placental system to independent functioning

Respiratory System Adaptations

• Initiation of breathing is crucial influenced by chemical, mechanical, thermal, and sensory factors
• Chemical factors stimulate the medulla's respiratory center because of relative hypoxia during birth
• Mechanical factors such as chest compression during vaginal delivery help expel fluid from the lungs
• Thermal factors stimulate breathing due to sudden temperature changes
• Sensory factors such as handling and drying the newborn also stimulate breathing
• The first breath requires a large amount of pressure to open the alveoli
• Surfactant, a phospholipid, reduces surface tension in the alveoli and prevents them from collapsing
• Normal respiratory rate for a newborn is 30-60 breaths per minute
• Breathing pattern is typically shallow and irregular
• Periodic breathing, includes pauses lasting 5-15 seconds without changes in color or heart rate, is common
• Signs of respiratory distress include nasal flaring, intercostal or xiphoid retractions, grunting, and seesaw respirations
• Central cyanosis, indicated by a bluish discoloration of the lips and tongue, is an abnormal finding

Cardiovascular System Adaptations

• Significant cardiovascular changes occur after birth including the closure of the foramen ovale, ductus arteriosus, and ductus venosus
• The foramen ovale closes due to increased pressure in the left atrium
• The ductus arteriosus constricts to increased oxygen levels and prostaglandins
• The ductus venosus closes when the umbilical cord is clamped
• Normal heart rate for a newborn is 110-160 beats per minute
• Blood pressure ranges from 60-80 mmHg systolic and 40-50 mmHg diastolic
• Acrocyanosis, or bluish discoloration of the hands and feet, is normal in the first 24 hours after birth
• Persistent central cyanosis is abnormal

Thermoregulation

• Maintaining a stable body temperature is vital for newborns
• Newborns are prone to heat loss because of a large surface area to body mass ratio, limited subcutaneous fat, and thin epidermis
• Mechanisms of heat loss:
  • Convection: Heat loss to the air
  • Radiation: Heat loss to nearby solid objects
  • Evaporation: Heat loss through vaporization of moisture
  • Conduction: Heat loss through direct contact with a cooler surface
• Non-shivering thermogenesis, the primary method of heat production in newborns involves the metabolism of brown adipose tissue (BAT)
• Cold stress can lead to increased oxygen consumption, respiratory distress, hypoglycemia, and metabolic acidosis
• Normal axillary temperature should be between 36.5°C and 37.5°C (97.7°F and 99.5°F)
• Interventions to maintain warmth include drying the newborn immediately after birth, using a radiant warmer, skin-to-skin contact, and swaddling

Hepatic System Adaptations

• The liver plays a crucial role in glucose regulation, bilirubin conjugation, and blood coagulation
• Newborns are at risk for hypoglycemia because of limited glycogen stores
• Normal blood glucose levels should be above 40 mg/dL
• Early feeding helps stabilize glucose levels
• Bilirubin is produced from the breakdown of red blood cells
• The liver conjugates bilirubin, which makes it water-soluble so it can be excreted
• Jaundice, or hyperbilirubinemia, is common in newborns because of the immature liver
• Physiological jaundice typically appears after 24 hours of age and resolves without treatment
• Pathological jaundice appears within the first 24 hours of age and requires intervention, for example phototherapy
• Vitamin K is produced by bacteria in the gut and is essential for blood clotting
• Newborns receive a vitamin K injection to prevent bleeding

Gastrointestinal System Adaptations

• The newborn's digestive system is immature
• Meconium, the first stool, is typically passed within 24-48 hours
• Meconium is thick, tarry, and dark green
• Transitional stools, greenish-brown and less sticky, occur after meconium stool
• Breastfed newborns typically have more frequent, seedy, yellow stools
• Formula-fed newborns have fewer stools that are pale yellow to light brown
• Regurgitation is common because of the immature cardiac sphincter
• Newborns can digest simple carbohydrates, proteins, and fats

Urinary System Adaptations

• The kidneys are immature, and newborns have a limited ability to concentrate urine
• Most newborns void within the first 24 hours
• The first void should be documented
• Urine may appear cloudy due to the presence of urates
• Dehydration can cause uric acid crystals in the urine, appearing as "brick dust staining" on the diaper
• The number of wet diapers increases to 6-8 per day after the first few days, indicating adequate hydration

Immune System Adaptations

• Newborns have limited immune function
• They receive passive immunity from maternal antibodies (IgG) that cross the placenta
• Breastfeeding provides additional antibodies (IgA)
• Newborns are at higher risk for infection

Behavioral Adaptations

• Newborns exhibit predictable behavioral patterns
• The Brazelton Neonatal Behavioral Assessment Scale (NBAS) is used to assess newborn behavior
• Six states of consciousness:
  • Deep sleep: difficult to arouse
  • Light sleep: more easily aroused
  • Drowsy: semi-dozing
  • Quiet alert: optimal state of arousal
  • Active alert: restless and easily startled
  • Crying: disorganized and agitated

Sensory Capabilities

• Newborns have well-developed senses
• Vision: can see objects 8-12 inches away, prefer faces and contrasting patterns
• Hearing: respond to noises, prefer human voices
• Smell: can distinguish mother's milk
• Taste: prefer sweet tastes
• Touch: sensitive to touch, find comfort in swaddling and holding

Periods of Reactivity

• First period of reactivity: lasts up to 30 minutes after birth; the newborn is alert and active
• Period of sleep: newborn becomes quiet and sleepy
• Second period of reactivity: lasts 2-8 hours, and the newborn is again alert and responsive

Nursing Interventions

• Monitor vital signs regularly
• Assess for signs of respiratory distress
• Maintain a neutral thermal environment
• Promote early breastfeeding or formula feeding
• Monitor for jaundice
• Provide skin care
• Promote bonding between parents and newborn
• Educate parents on newborn care