Physiological Adaptations to Birth

Physiological Adaptations to Birth

1. Respiratory System

   • • Mechanical stimuli
     • Fetal gasp occurs during expulsion and is initiated by a central nervous system trigger in response to the sudden change in pressure and temperature. Fetal chest compression and chest recoils occur during expulsion
   • Chemical stimuli
     • Transitory asphyxia occurs due to: – Increase in PCO 2 – Decreases in pH and PO 2
   • Other stimuli
     • Changes in temperature stimulate skin sensors and rhythmic respirations occur . Environmental components include tactile, auditory, visual, and pain stimuli.

2. CARDIOVASCULAR SYSTEM

   • • The initial breath at birth decreases pulmonary vascular resistance, increasing blood flow to the lungs. • Blood returning from the pulmonary veins increases pressure in the right atrium.

3. Hematological System

   • • Increase in catecholamines results in increased cardiac output required for maintaining increased metabolic oxygen needs related to thermogenesis, breathing, and feeding demands. • Fetal right-sided dominance switches to left-sided dominance by 3 to 6 months of age.

4. HEPATIC SYSTEM

   • Iron storage for new RBC production
     • Prenatally, if the mother’s iron intake has been adequate, there is enough iron stored to last 5 months. At around 6 months of age, food containing iron and/or iron supplements must be added to the infant’s diet.
   • Coagulation
     • The absence of normal flora needed to synthesize vitamin K results in low levels of vitamin K and creates a transient blood coagulation alteration between the second and fifth days after birth
   • Carbohydrate metabolism
     • The newborn cord blood glucose level is 15 mg/dL lower than maternal blood glucose. The newborn’s carbohydrate reserve is relatively low
   • Conjugation of bilirubin
     • Conjugation is the conversion of bilirubin from the yellow fat-soluble, unconjugated/indirect form into a water-soluble, excretable/direct form.

5. GASTROINTESTINAL SYSTEM

   • • The newborn’s stomach holds about 50 to 60 cc and can pass meconium 24 to 48 hours after birth. • Permeability—The newborn’s intestines lack the protective mucosal barrier that helps seal off the intestines, decreasing the risk of both bacteria and potential allergens permeating through the intestine into the bloodstream.

6. URINARY SYSTEM

   • • Many newborns void immediately after birth and 90% by 24 hours of life. A newborn who has not voided by 48 hours of life should be evaluated for adequacy of fluid intake or urinary/bladder abnormality or dysfunction. • Normal urine is straw colored and odorless.

7. IMMUNOLOGICAL SYSTEM

   • There is little immunity to herpes simplex virus (HSV), so caretakers with an active HSV infection need to wear a mask and gloves.

8. NEUROLOGICAL SYSTEM

   • First alert period: (15–30 minutes after birth) Baby is alert, respirations irregular, responds vigorously to stimulation Resting period: (30–120 minutes after birth) Color and vital signs are stabilizing, baby sleeps and is difficult to arouse Second alert period: (4–8 hours after birth) Awakening, becoming responsive to stimuli again, may have a lot of mucus to clear
   • Behavioral States
     • 1. Quiet sleep Deep sleep, no eye movement, respirations quiet and slower 2. Active sleep Rapid eye movements, may move extremities or stretch 3. Drowsy Transitional period, yawns, eyes glazed 4. Quiet alert Infant able to focus on objects or people, tuned in to environment 5. Active alert Restless, starting to fuss, faster respirations, more aware of discomfort
   • Senses
     • Touch The most significant sense in the newborn for the first few weeks of life. Vision Newborns can see objects 8 to 12 inches from their eyes. Newborns are most drawn to faces, particularly the eyes. They are able to follow objects to center of visual field. They prefer yellow and red objects and will regard moving objects and changing light intensity. Hearing The newborn will turn toward the sound of a voice and tends to be more alert to a high-pitched voice. Taste They are able to discriminate between sweet/nonsweet. Smell The newborn’s ability to smell increases over the first few days of life. The newborn is able to identify mom’s breast milk.

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