physiological adaptions

• Neonatal period

  Birth through day 28 of life
• Newborn physiologic tasks

  • Establishing and maintaining respirations
  • Adjusting to circulatory changes
  • Regulating temperature
  • Ingesting, retaining and digesting nutrients
  • Eliminating waste
  • Regulating weight
• Newborn behavioral tasks


  • Establishing a regulated behavioral tempo independent of mom
  • Self-regulating arousal
  • Self-monitoring changes in state and patterning sleep
  • Processing, storing and organizing multiple stimuli
  • Establishing a relationship with caregivers and environment
• Stages of transition to extrauterine life

  1. First period of reactivity (up to 30 minutes after birth)

  2. Period of decreased responsiveness (60 to 100 minutes after birth)

  3. Second period of reactivity (2 to 8 hours after birth)
• First period of reactivity

  • Newborn's HR increases to 160 to 180 but gradually decreases after 30 minutes, infant is alert
• Period of decreased responsiveness


  • Newborn either sleeps or has a marked decrease in motor activity
• Second period of reactivity

  • Tachycardia or tachypnea, increased muscle tone, improved skin color pushing out the acrocyanosis, mucous production, meconium typically passed
• Respiratory adaptations

  1. Mechanical changes

  2. Chemical changes

  3. Thermal changes

  4. Sensory changes
• Mechanical changes

  • Lung fluid volume decreases as labor approaches, 80-110 mL that remain must be removed, chest compression and increased thoracic pressure removes fluid with vaginal birth, gasp and forced exhalation removes some fluid, breathing distributes air in lungs and promotes expansion
• Chemical changes

  • Increased PCO2 and decreased pH and pO2 triggers chemoreceptors of the brain's respiratory center to continue respirations, associated with umbilical cord clamping and loss of placental source of oxygen, brief asphyxia stimulates respirations, excessive asphyxia depresses respirations
• Thermal changes

  • Significant temperature drop at birth stimulates skin nerve endings to cause rhythmic respirations, excessive cooling can lead to hypothermia cold stress and respiratory depression, skin to skin stabilizes body temperature and provides warm to sustain respirations
• Sensory changes

  • Stimulation further triggers respiratory centers to continue respiratory drive, tactile stimulation like touch sensation of gravity and unrestricted limb movement, visual, auditory
• Normal newborn respirations

  • Transition often takes several minutes to a few hours
  • Normal rate is 30-60
  • Diaphragmatic and generally shallow
  • Obligate nose breathers this shifts about 3 weeks of age before then nasal congestion is dangerous
  • Has synchronous abdomen and chest rise
  • Acrocyanosis is normal finding in first 24 hours after birth
  • Irregular depth and rhythm periodic breathing like pauses of 5-15 secs w/o color or HR change is normal
• Abnormal newborn respirations

  • Tachypnea > 60 is the first sign of distress
  • Apnea greater than 20 seconds possible with bradycardia cyanosis grunting flaring nostrils retractions see saw respirations hypotonia (late sign)
• Give caffeine

  To stimulate respiratory drive
• Cardiac adaptations

  1. Reduced pulmonary vascular resistance, pulmonary artery and right atrium pressure decreases

  2. Increased pressure form left side of heart closes foramen ovale

  3. CO increases and increase circulatory volume to lungs guts kidneys

  4. Increased oxygenation helps close ductus arterious

  5. Clamping umbilical cord functionally closes ductus venous, ductus arteriosus and ductus venous turn into ligaments
• Signs of cardiovascular problems

  • Persistent tachycardia first sign
  • Persistent bradycardia < 80
  • Skin color of pallor or cyanosis centrally
• Thermoregulation

  Maintenance of balance between heat loss and heat production, important in the first 48 hrs, newborns struggle to thermoregulate and are high risk for either hypo or hyperthermia, high surface area (lower body weight), limited fat stores, new metabolism
• Hyperthermia

  Less common but required education for avoidance
• Causes of hypothermia

  • Heat loss by convection, radiation, evaporation, conduction
• Non-shivering thermogenesis

  Newborns have brown fat stores that can be used and burned as needed
• Goal of care is to establish a neutral thermal environment to infant
• Cold stress


  • Increases O2 consumption and increase RR, increase RR causes peripheral vasoconstriction leading to decrease O2 to tissue, both of these lead to increase in anaerobic glycolysis burning more sugar and decrease in PO2 and pH causes metabolic acidosis
  • Increase in RR also causes pulmonary vasoconstriction which decreases O2 uptake by lungs
• Gastrointestinal system adaptations

  • Blood glucose starts dropping as soon as the cord is cut and reach a low point between 30-90 minutes after birth
  • Breastfeeding is important in establishing the microbiome of the newborn
  • Feeding behavior is related to gestational age, neuromuscular maturity, maternal medications during labor and birth, type of initial feeding
  • Stomach has limited capacity on day one and slowly expands to about 90 mL by day 3
  • Bowel sounds are already present at birth, require burping after feedings, spitting up is normal due to reflux
  • Meconium has fully passed within 48 hrs, not by 24 need to further investigate
  • Normal weight loss of 5-8%, regain birth weight by 10-14 days of age
• Hepatic adaptations

  • Iron storage - fetal liver begins storing iron in utero, fetal stores last until about 4 months of age
  • Glucose homeostasis - have high glycogen reserve for transition, can be rapidly depleted
  • Coagulation - lack of intestinal bacteria needed to synthesize vitamin K results in transient blood coagulation deficiency between the second and fifth days of life, risk for hemorrhage, vitamin K injection
  • Fatty acid metabolism, bilirubin synthesis which is the liver's job
• Immune system

  • Compared to adults the immune response at birth is reduced leading to increasing susceptibility to pathogens, many components of breast milk strengthen neonate's immune system
  • Neonatal levels of circulating immunoglobulins are low - IgG passive acquired via placenta during last month of pregnancy, IgM suggestive of intrauterine infection, IgA passive acquired via colostrum against respiratory and GI infections
  • Greatest risk factor for neonatal infection is prematurity, IgG dumps in last 4 weeks of pregnancy
• Integumentary system findings

  • Vernix caseosa- white on baby
  • Sweat glands/milia: pimple on nose
  • Desquamation: peeling skin
  • Mongolian spots: blue butt
  • Nevi-port wine stains
  • Infantile hemangioma- raised birth marks
  • Erythema toxicum- looks like allergic rx
• Reproductive system findings

  • Female - pseudomenstruation from withdrawal of maternal hormones, usually within first month only happens one time
  • Male - testes are not always descended often transiently descended
  • Swelling of breast tissue or excrete liquid - caused by hyperestrogenism of pregnancy and subsides within a few days
• Signs of reproductive problems

  • Ambiguous genitalia
  • Hypospadias
  • Undescended testes
  • Inguinal hernias
• Skeletal system findings

  • Head and skull - molding, caput succedaneum (edema on the scalp), cephalhematoma (bleeding within the skin one area scalp WONT cross suture lines), subgaleal hemorrhage (bleeding crosses suture lines)
  • Extremities - oligodacyly, polydactyly, syndactyly, developmental dysplasia of the hips
• Sign of skeletal problems is asymmetry
• Behavioral characteristics

  • Regulate their physiologic or autonomic system
  • Regulate or control their motor behavior
  • State regulation with state of consciousness
  • Attention and social interaction
• Sleep wake states

  Six states form continuum from deep sleep to extreme irritability, ability to make smooth transitions between states is called state modulation
• Factors influencing newborn behavior

  • Gestational age
  • Time
  • Stimuli
  • Medication