Newborn Physiological Adaptation and Thermoregulation

Physiological Adaptations

• Fetal preparation for extrauterine life involves the maturation of fetal lungs
• Surfactant is produced, consisting of a mix of phospholipids and lipoproteins
• Brown fat is deposited; it regulates body temperature in infants
• Glucose is stored in the liver as glycogen, providing an energy source for the newborn
• The adrenal glands produce catecholamines, including dopamine, norepinephrine, and epinephrine

Thermoregulation System

• There is a risk of hypothermia in infants as their body temperature is often below normal

• Evaporation, loss of heat occurs as amniotic fluid on an infant evaporates

• Conduction, transfer of heat occurs from an infant's body to cooler surfaces

• Convection, transfer of heat occurs from the infant's body heat to surrounding cool air

• Radiation, transfer of heat occurs from the infant's body heat to a cooler object not in direct contact

• Lack of subcutaneous fat and blood vessels close to the surface, causes problems with heat regulation

• Infants use brown fat to provide additional heat

• Metabolism of brown fat leads to nonshivering thermogenesis

• Rapid metabolism of brown fat from cold stress can result in metabolic acidosis

• An increased metabolic rate in a cold newborn increases the need for oxygen, decreases surfactant production, and elevates the use of glycogen leading to hypoglycemia

Nursing Interventions for Thermoregulation

• Drying immediately after birth
• Skin-to-skin contact with the mother
• Covering the head
• Monitoring temperature every 15 minutes for the first hour
• Avoiding uncovering or exposing the entire body
• Place the baby under a preheated radiant warmer
• Bathe the baby after temperature has been stable for at least 2 hours
• Cribs should be placed away from drafts or windows

Respiratory System

• Breathing requires a sequence of events and internal and external stimuli to occur

• Internal stimuli are chemically focused

• External stimuli include mechanical, sensory, and thermal changes

• Breathing at birth: chest pressure squeezes out secretions and amniotic fluid

• Chest recoils, causing air to fill the lungs

• There is an increase of surfactant to keep alveoli open after initial breaths

• The cutting of the umbilical cord causes respiratory centers in the brain to begin working due to a drop in blood pH

Nursing Interventions

• Count respirations per minute
• Suction mouth and nose
• Monitor respiratory effort
• Observe abdomen

Cardiovascular System

• There are circulation changes during newborn transition
• After newborn starts breathing, blood flow changes
• Breakdown of RBC increases and bilirubin is released
  • Bilirubin is a waste product of breakdown of RBCs
• Elevated WBCs and absence of vitamin K are common

Nursing Interventions

• Monitor heart rate
• Positive pressure ventilation can be used to increase heart rate
• Begin chest compressions if heart rate falls below 60 bpm
• Monitor color of the trunk, mucous membranes, and the capillary refill time

Renal System

• Kidneys are immature
• Urine is not concentrated until 6 weeks old
• Urine is odorless and a light color or clear
• Volume within 24 hours of birth is about 15 mL
• Total daily output for the first 2 days is 30-60mL
• Volume rises to 300 mL per day

Nursing Interventions

• Monitor first void
• Weigh diapers
• Encourage frequent breastfeeding

Gastrointestinal System

• Sterile at birth
• When bacteria enters the body, they become probiotics. Intestinal bacteria aids in digestion and synthesizes Vitamin K
• The capacity of a newborn stomach is 60-90 mL
• Pancreas is immature
• Cardiac sphincter between esophagus and stomach is weak
• Meconium stool is expelled within 24-48 hours of birth

Nursing Interventions

• Monitor for meconium stool; report if not expelled within 24 hours
• Educate individuals to avoid overfeeding
• Educate them about immature cardiac sphincter and regurgitation

Hepatic System

• Liver immature at birth with a high number of unneeded RBCs
• If not removed efficiently, normal physiological jaundice occurs by day 2-4
• Liver job is to remove indirect (unconjugated) bilirubin and convert/conjugate it to a form that can be excreted
  • Indirect bilirubin causes jaundice with yellow discoloration of skin
• Once conjugated, direct (conjugated) bilirubin is excreted into the common duct, duodenum, and a small amount in urine

Nursing Interventions

• Monitor for yellow sclera and skin
• Educate about normal physiological jaundice

Immune System

• They are born with passive antibodies (immunoglobulin G)
  • Protects for 2-4 months
• Antibodies are not produced until about 2 months of age

Nursing Interventions

• Strict hand washing
• Protect from infection
• Screen health-care personnel and visitors for illness
• Teach hand hygiene
• Encourage immunizations to begin at 2 months of age

Behavioral Adjustment to Extrauterine Life

• Newborns initiate interaction by crying, quiet when soothed, and engage in mutual gazing
• The newborn likes something when focusing eyes and tracking objects or a person
• The newborn shows dislike when turning away, crying, or yawning
• They self-soothe by thumb or hand sucking
• Every baby is different

Periods of Reactivity

• First period: 30-60 minutes after birth, alert, active, cooperative with a vigorous suck reflex
• Period of inactivity: falls into a deep sleep for 2-4 hours or longer and is unresponsive to external stimuli
• Second period: wakes up from long sleep, alert, active, and hungry

Newborn Behaviors

• Deep sleep
• Light sleep
• Drowsy
• Alert
• Active alert
• Crying