Physiological Change in Newborn Baby

After the final stage of gestation and for the first month, a newborn infant is referred to as a neonate. A baby from birth to the 28th day of life is referred to as a neonate or newborn. The first week of life (seven days or 168 hours) is referred to as the neonatal period. The late neonatal period lasts from the seventh to the twenty-eighth day. A healthy newborn delivered at term (between 38-42 weeks) should have an average birth weight for the country (typically greater than 2-5kg) and cries immediately after birth, establishing interdependent rhythmic respiration and rapidly adapting to the changed surroundings.

Physiological change in newborn baby

Respiratory system
The establishment and commencement of respiration are critical to the survival of newborns. Effective induction of respiration tests the integrity of the neonate's respiratory, cardiovascular, and central neurological systems, and is best accomplished when these systems are both physically and functionally normal. A patent airway is required for pulmonary breathing.

The respiration is initiated because of the following mechanism.

• The respiratory tract contains around 20mg/kg of lung fluid at term. Prior to the commencement of labor, some fluid absorption occurs on the lungs.
• Compression of the chest wall during delivery aids in the ejection of some of the leftover fluid. Residual lung fluid may contribute to the newborn's temporary tachypnea.
• Surface tension in the lungs is reduced by the presence of surfactant.
• Stretch receptors in the lungs are stimulated by compression of the chest wall during delivery, followed by elastic recoil of the thorax when the body is delivered.
• The compression and decompression of the body's head during delivery is thought to excite the respiratory center in the brain, which in turn keeps the stimulus to respiratory effort going.
• Tactile stimulation is thought to be of low importance.

Circulatory system

The following are some of the transient structures found in the deadly blood circulation:

• Ovale foramen
• A gap between the two atria that allows blood to pass from the right to the left atrium.
• A shunt between the pulmonary artery and the aorta is known as a ductus arteriosus.
• Ductus Venosus is a shunt that connects the umbilical vein to the inferior vena cava (from a vein to vein)
• The Hypogastric Arteries
• When they enter the umbilical cord, the branches of the internal iliac arteries become known as umbilical arteries.
• The umbilical vein runs from the umbilical cord to the underside of the liver, carrying oxygenated and nutrient-rich blood.
• It has a branch that connects to the portal vein and nourishes the liver.

The fatal circulation changes shortly after birth as a result of:

• Cessation of the placental blood flow.
• Initiation of respiration

The vascular system undergoes the following changes:

Closure of the foramen ovale:

• When an infant is carried, the lungs enlarge and the vascular area expands.
• This lowers the pulmonary vascular resistance.
• The pressure in the left atrium rises when all of the cardiac output from the lungs is directed to the heart.
• At about the same time, blood flow through the cord stops, lowering pressure in the right atrium.
• As a result, functional closure of the foramen ovale occurs shortly after birth, although physical closure takes roughly a year.
• Perfect anatomical closure may never be achieved in the same individuals.

Closure of the duct arteriosus

• Within a few hours of breathing, the muscle wall of the duct arteriosus contracts, most likely in reaction to growing Oâ tension and a decrease in circulating prostaglandin levels.
• After the development of pulmonary circulation, functional closure of the ducts may occur; morphological obliteration takes around 1-3 years and becomes ligamentum arteries.

Closure of the umbilical vein:

• It takes place a little later than the arteries.
• The ductus venous collapses, and venous pressures in the inferior vena cava and right atria fail.

Closure of the umbilical arteries:

• A functional enclosure prevents even a minor amount of fetal blood from draining out almost promptly and very quickly.
• The actual obliteration process takes roughly 2-3 months.
• The distal end produces the lateral umbilical ligaments, whereas the proximal end remains open as superior vesical arteries.

Hypogastric arteries

• Close effectively within a few minutes of birth and cord clamping.

Thermal adaptation

A delivery room temperature of 24°C contrasts dramatically with intrauterine temperature and prevents the newborn from rapidly chilling when amniotic fluid evaporates from his skin. Every millimeter that evaporates absorbs 560 calories of heat. The newborn's subcutaneous fat layer is thin and provides poor insulation, allowing for quick transfer of core heat to the skin and the surroundings, as well as cooling of his blood.

The heat-regulating center in the baby's brain has the ability to boost heat generation in response to thermoreceptor stimulation. In times of cold stress, the newborn possesses brown adipose tissue, which aids in the quick mobilization of heat resources, mainly fatty acids and glycerol. This process is known as non-shivering thermogenesis. Brown adipose tissue can be found in the mediastinum, the nape of the neck, between the scapulae, the spinal column, and the suprarenal region.

Hemopoietic system

The amount of placental transport determines the blood volume. The blood volume per kilogram of body weight is 80-85 mL. The typical volume immediately after birth is 300ml. The average RBC count per mm3 is 5 million. The average Hb level is 16-20mg/dl, the hematocrit is 45-60mg/dl, and the WBC count is 20000mm3.

Physical features and characteristics of newborn

1. General appearance
   The color of the baby is pinkish-red. Vernix caeseosa is a white creamy, natural covering of the fetus's skin during the third trimester of pregnancy.
    
2. Posture
   The infant will have flexed limbs and clenched hands.
    
3. Skin
   Slight peripheral skin cyanosis is extremely common, although it quickly becomes pinkish when cardiopulmonary function is restored. Vernix has a protective effect and is mostly absorbed within a few hours.
    
4. APGAR score
   A typical newborn should have an Apgar score of 7-10. A score of less than 7 indicates suffocation.

1. General appearance
    
2. Weight:
   A newborn baby's usual weight ranges between 2.5 and 3 kg. The loss of 100-200gm weight on the second day of birth is due to fluid loss due to physiological loss, a lack of fluid intake, and fluid loss in the form of meconium and urine.
    
3. Length:
   The typical length of a normal infant is 50-52 cm. The baby is measured from head to toe.
    
4. Head circumference:
   The circumference of the head is measured by wrapping a measuring tape around the occipital protuberance at the supraorbital ridge. The usual circumference of the head is 33-35 cm.
    
5. Chest circumference:
   The chest is smaller in size than the head. A normal chest circumference is 30-31cm. The nipple spacing should be documented.

Fig: general measurement

1. Face
   The face is much smaller than the skull. Most of the time, the eyes are closed, and a papillary light reflex is present. The gums are silky. Fat-sucking pads have filled the cheeks.
    
2. Genitalia and breasts
   Breast tissue nodules surround the nipple in both boys and girls. In boys, the testicles descend into the scrotum, which is covered in rugae. The prepuce has attached to the glans and the urethral meatus has opened at the tip of the penis. The labia majora normally covers the labia minora in girls born at term. The hymen and clitoris may appear excessively big.
    
3. Physiological changes
    
4. Respiratory system
   The fetus receives oxygen in the uterus via the placenta. The average baby breathes at a pace of 30-60 breaths per minute.
    
5. Thermal regulation
   Thermal control in neonates has been poor for some time. Infants are in danger of hypothermia due to poor temperature regulation caused by a variety of factors such as surroundings, cold, and the need to keep warm.
    
6. Cardiovascular system
   After birth, the fetal circulation changes. The heart rate is rapid (120-140 beats per minute) and fluctuates according to the baby's function, activity, or sleep condition.
    
7. Renal regulation
   In prenatal life, the kidneys function normally. The rate of glomerular filtration is poor, and tubular reabsorption capacity is limited.
    
8. Gastrointestinal system
   Sucking and swallowing reflexes are most noticeable after birth, and they are coordinated. Meconium should be passed within 2-3 days of birth, followed by a mustard-colored stool after 4-5 days.
    
9. Immunological system
   IgG, IgA, and IgM are the three primary types of immunoglobulin. It protects the infant for up to two months. Breast milk, particularly colostrums, provides the infant with passive immunity in the form of lactobacillus difidus.
    
10. Neurological adaption
    After birth brain growth is rapid requiring constant and adequate supplies of oxygen and glucose. There is various reflex are:

• Moro reflex:
  It can be provoked by holding the baby at a 45-degree angle and allowing the head to sink 1 or 2 cm.
• Rooting reflex:
  In reaction to stroking on the cheeks or the side of the mouth, the baby will turn towards the stimulus and open his lips to suckle.
• Sucking and swallowing reflexes:
  These are highly developed in a normal newborn and work in tandem with breathing. This is critical for proper nutrition and safe feeding.
• Gag, cough, and sneeze reflex:
  Avoid obstructing the infant's airway.
• The eyes are protected against trauma via blinking and corneal reflexes.
• Grasp reflexes:
  Placing a finger or pencil in the palm of the baby's hand elicits a palmer hold. The finger is securely grabbed.
• Walking and stepping reflexes:
  The baby facilitates walking when he is supported upright and his feet are contracting a flat surface. If the infant is held with the tibia in touch with the edge of a table, he or she will step up onto the table (limp-placement reflex).
• Traction response:
  When the wrist pulls the head upright to a sitting position, it will lag at first, then right itself monetarily before sliding forward onto the chest.
• Ventral suspension:
  When the baby is held prone suspended over the examiner's arm, he flexes his limbs and holds his head level with his torso for a brief while.

Special senses

• Vision:
  Vision is present and functional at birth, even if it is undeveloped. The baby is quite sensitive to birth lights. When being nursed, his focusing distance is 15-20cm, allowing him to view the mother's face.
• Hearing:
  When the baby hears a high-pitched sound, he turns his head and gazes at it.
• Smell and taste:
  Babies prefer the fragrance of milk to that of other substances, and they prefer human milk.
• Touch:
  Infants are extremely tactile, and they prefer skin-to-skin contact, immersion in water, caressing, hugging, and rocking movements.