Physiological Adaptations of the Newborn and Newborn Assessment

Three stages of physiological adaptions (newborn)

1. First period of Reactivity

2. Period of decreased responsiveness

3. Second Period of reactivity

• All three stages occur during the first 6 – 8 hours

• Stages are mediated by the CNS – HR, Resps, Temp, GI function

How long does the first period of reactivity last?

lasts up to 30 minutes after birth

First period of reactivity: physiological adaptions

• Newborn's heart rate increases to 160 to 180 beats/min

• Respirations may be irregular: 60 to 80 breaths/min (there may be fine crackles, grunting, nasal flaring, and retractions) →d/t coughing up fluid in their lungs

• Baby is alert, with spontaneous startle reflex, tremors, crying, movement of head

• Bowel sounds present, may pass meconium 

• Followed by a decrease in motor activity and sleep

How long does the period of decreased responsiveness last?

Lasts 60 to 100 minutes or 2 to 2 ½ hours

Physiological Adaptation:Period of decreased responsiveness

• baby is usually asleep at this time

• nurse is with mother for first 2 hrs - for 15 min checks on both mom and baby

• skin to skin is usually occurring at this time

• usually first breastfeeding is done at this time

• Mom gets waist down cleaning

How long does the second period of reactivity last?

lasts 10 minutes to several hours

• occurs 2 to 8 hours after birth

Visitors during the Second period of reactivity

• assess if baby is tolerating the visitors well

• indication: fussiness and crying (late sign)

• if baby and mother aren’t coping well, nurses can say something

• can impact 2nd period of reactivity if baby constantly being passed around for hours

Newborn Feeds

awake or not awake need to feed every 1-3 hours (will wake up, if awake be fussy and unhappy) 

Second period of reactivity: physiological adaptions

• Tachycardia, tachypnea may occur

• Meconium commonly passed 

• Increased muscle tone, changes in skin color, and mucus production

• Baby will be hungry and interested in feeding

Initiation of breathing and maintaining adequate oxygen supply:Chemical Factors

neonate assumes responsibility for all gas exchange and metabolism

• decreased levels of oxygen and increased levels of CO2 – stimulate respiration center in medulla and drop in prostaglandin levels can inhibit resps.

Initiation of breathing and maintaining adequate oxygen supply:Mechanical

Intrathoracic pressure changes as circulatory system becomes independent

• results from compression of chest during vag birth. Negative intrathoracic pressure helps draw air into lungs. Crying increased distribution of air into lungs and promotes expansion of alveoli. Positive pressure keeps alveoli open.

Initiation of breathing and maintaining adequate oxygen supply:Thermal

 initialization of breathing

• exposure to air temp stims receptors in the skin leads to stim of resp center

Initiation of breathing and maintaining adequate oxygen supply:Sensory

handling, drying infant, lights, smells, sounds

• sensory stim with drying, handling lights,

• Preceding labour: decreased production of fetal lung fluid and decreased alveolar fluid volume. Just before labour, there is a catecholamine surge which seems to promote clearance from the lungs

Signs of Respiratory Distress - From retention of lung fluid

• Fluid retention more likely in a C/S delivery

• Remember neonates may have irregularities in breathing at first

• Respiratory Distress = nasal flaring, intercostal or subcostal retractions 

  • Evaluated RR < 30/min or > 60/min

  • Central cyanosis is a late sign of distress (lips & mucous membranes blueish)

Respiratory System: In Utero

transplacental gas exchange with fetal blood shunted away from lungs. 

Why does cord clamping cause an increase in blood pressure?

increases circulation and lung perfusion

Respiratory System: premature baby

 problems d/t immature lungs & gestational age

Respiratory system: cord clamping

cord is clamped and cut →rapid physiological changes →establishment of spontaneous respirations

Transient tachypnea of the newborn (TTN,TTNB)

• respiratory problem that can be seen in the newborn shortly after delivery

• retained fetal lung fluid due to impaired clearance mechanisms

• diagnosed in the first few hours

•  Transient means it does not last long, usually 1-2 hours (less than 24 hours)

• Tachypnea refers to the baby's faster-than-normal breathing (more than 60 breaths per minute)

Signs and Symptoms: Transient tachypnea of the newborn (TTN,TTNB)

• intermittent grunting

• nasal flaring

• mild retractions – supplement with oxygen or ventilator support

Spontaneous startle reflex

•  expand arms and legs, surprise themselves since not used to having limbs

Physiological Adaptions: Cardiovascular System

• pulmonary artery pressure decreased, and pressure in the right atrium decreased

  •     decerased Pulmonary blood flow and closure of the foramen ovale (normal opening between atria that closes at 6 months)

• Blood Volume – 300 mL (can increase by 100mL, depends on length of time of cord clamping and cutting)

Ductus arteriosis

• constricts with increased oxygen and prostaglandin

• closes within first hours after birth (permanently closes within 3 – 4 weeks)

• Becomes a ligament

• It can reopen in response to low oxygen levels (hypoxia, asphyxia, prematurity)

Cardiovascular System: Vital Signs

• Heart rate and sounds – apical (4^th intercostal space)

  • BP = 60 – 80 systolic/ 40 – 50 diastolic (for a term newborn) 

  • Variations in 1^st month

Signs of cardiovascular problems

•  murmur, cyanosis, pallor with murmur, 

• Persistent tachycardia (> 160 bpm) due to anemia, hypovolemia, hyperthermia, sepsis

• Persistent bradycardia (< 100 bpm due to congenital heart block, hypoxemia, hypothermia)

Cardiovascular System: Premature

Blood volume greater due to greater plasma volume (not greater RBC)

Meconium

• by 8 hours, red flag if no poop by 8 hours 

  • empty bowels except for meconium

  • 8 hours (should have been 3 feeds roughly) something should have gone into the babies mouth and something should be coming out 

  • looking for 1 poop in 24 hours; if not, look into the feeding situation 

Fetal circulation

• less efficient at oxygen exchange than the lungs so fetus needs additional RBC for transport of oxygen in utero

• At birth, average levels of RBC and Hgb are higher than in an adult.

• Levels drop over 1^st month. 

Delayed Cord Clamping

• delayed oxygenation - baby can breathe on their own, but mom can still do oxygenation through cord

• cord blood has a lot of nutrients in it (300ml is not a lot)

Physiological Adaptions: Hematopoietic system

• Red blood cells (4.8 – 7.1X1012 /L) and hemoglobin (137 – 201g/L) are increased

• Leukocytes - increased during 1^st day and then decreases rapidly 

• Platelets – newborns are the same as adults except platelet factors in the liver in 1^st days of life mean newborns cannot synthesize Vitamin K

Vitamin K prophylaxis

• newborns cannot synthesize Vitamin K d/t non-functioning platelets

• Vitamin K injection in first hours to assist with clotting

• IM to prevent hemorrhagic disease of newborn (HDN)

Newborn Blood group

• is determined via cord blood samples along with potential for hyperbilirubinemia (bilirubin is a product of RBC breakdown and neonates cannot get rid of it easily)

Physiological Adaptions: Thermogenic Systems

• Heat Loss –heat transfer from newborn to environment

  • Temp & humidity of air, air flow, temp of surfaces

  • Goal – neutral thermal environment

  • Convection, Radiation, Evaporation, Conduction

• Skin to skin contact – reduces heat loss, enhances temp & bonding

Thermoregulation

• the balance of heat production and loss

• conserve heat in position of flexion to guard against heat loss (diminishes body surface exposed to environment

  • vasoconstriction of peripheral blood vessels

  • No shivering mechanism!!!
    

Thermogenesis

• Internal attempts to generate heat (cellular metabolic activity in brain, heart and liver increases oxygen and glucose consumption)

  • Brown fat - Non-shivering thermogenesis occurs through the metabolism of brown fat

    • Located in interscapular region, axillae, thoracic inlet, vertebral column, around kidneys

    • Amount increased with gestational age

Cold Stress

increased RR with oxygen needs → leads to vasoconstriction →can decrease pulmonarynperfusion → reopen R to L shunt across ductus arteriosus

Hyperthermia

• Temp > 37.5 (99.5 F) due to excess heat production or sepsis

• (radiant warmers, phototherapy, sunlight, increased environmental temp, excess clothing – vasoconstriction)

Hypothermia

• common d/t thin layer of subcutaneous fat and blood vessels are close to skin surface.

• Also changes in environmental temperature alter temp of blood & influencing temp regulation center in hypothalamus. 

• Newborns have larger body surface to wt. mass ratios = Heat Loss Quickly

Convection

flow of heat from body surface to cooler ambient air.

• Need warmer ambient temps→use:

  • overhead warmers

  • wrap baby in blanket

  • hats (if in open bassinets).

Conduction

heat loss from body surface to cooler surface (touch)

• heat loss d/t being in contact with a cold surface

(Use protective cover on weigh scales)

Radiation

loss off heat from body surface to cooler not in direct contact with newborn (position exam tables, bassinets away from open windows or direct air drafts)

Evaporation

• loss of heat when liquid converted to a vapour

• moisture vaporization from skin:

  • be sure to dry skin of newborn after birth/bath quickly

• The less mature the more evaporative heat loss

• Component of insensible water loss

Physiological Adaptions: Renal System

• Most newborns void at birth (can be missed)

  • 1^st day = 1 void 

  • 2^nd day = 2 voids

  • 3^rd day = 3 voids

  • 1 week – 6 – 8 voids 

• Uric acid crystal stains can occur, watch for persistence

Renal system: Weight loss

 5 – 10 % wt. loss in 1^st 3 – 5 days is normal due to urine, feces, lungs, increased metabolic rate, intake (colostrum is high fat but not high volume)

Renal Systems: Fluid and Electrolyte Balance

• 75% body wt. total body water (extracellular & intracellular)

  • Daily fluid intake requirements (ex. 1500 gm neonate = 60 – 80 ml/kg/d)

  • Lower GFR with less ability to remove nitrogenous & waste products from blood.

Signs of renal system problems

• lack of steady stream

• hypospadias (urethral opening on underside of penis)

• epispadias (opening on top or side)

Gastrointestinal System: Digestion

• Term newborns are able to swallow, digest, metabolize & absorb proteins, simple carbs & emulsifying fats

• Enzymes & digestive juices are present in term & LBW infants {except pancreatic amylase & lipase)

Digestion process

• Amylase is produced by salivary glands after 3 months & by pancreas at 6 months.

  • Amylase converts starch into maltose (high amounts in colostrum)

• Lipase is needed for digestion of fat

  • Mammary lipase in human milk aids in digestion of fats for newborn

• Bacteria not present in GI track at birth. 

  • Entrance of bacteria through oral & anal orifices and air

  • Stomach capacity = up to 30 ml (Day 1) = up to 90 ml (end of first week of life)

Stool (Meconium)

•  greenish/black because it contains occult blood

  • sterile at birth; contains bacteria within a few hours

  • early frequent feeds assist in removing stools (also assists with jaundice)

Signs of gastrointestinal problems

• No stools (bowel obstruction, imperforated anus) 

• White stools (biliary atresia is blockage in tubes carrying bile from gallbladder to liver)

Newborn Sucking

• Sucking begins at 15 – 16 weeks in utreo

• Sucking behavior influenced by neuromuscular maturity, mat medications in L&D, type of initial feeding.

• Small bursts of 3-4 up to 8 – 10 sucks at a time with brief pauses. Unable move food from lips to pharnx so important to place nipple well inside mouth

Gastrointestinal System

• Peristalsis in esophagus uncoordinated in 1^st days but quickly coordinated in healthy full-term

• Large amounts of mucous are present in the first hours after birth. 

• Hydrated infants – mucous membranes moist & pink, hard and soft palates are intact.

Newborn Mouth/Teeth

• Small whitish areas (Epstein pearls) found on gum margins and juncture of hard and soft palates

• Cheeks full d/t developed sucking pads – disappear approx. 12 months

• Teeth –>begin developing in utero

  • enamel formation until approx. 10 years

  • Can have natal teeth have poorly formed roots and are often extracted d/t risk of aspiration.

Epstein Pearls

Small whitish areas found on gum margins and juncture of hard and soft palates

Changes in Stooling Patterns: Meconium

Meconium = first stool, complete passage occurs between 24-48 hrs to 7 days 

Changes in Stooling Patterns: Transitional Stools

Day 3 (after initiation of feeding) 

• Greenish-brown to yellowish-brown. May contain milk curds.

Changes in Stooling Patterns: Milk Stools

Day 4

• BF = yellow to golden, pasty (mixture of mustard & cottage cheese), smell of sour milk

• Formula Fed = pale yellow – light brown, firmer consistency, more odor

Physiological Adaptions: Hepatic System

• Liver & gallbladder formed by 4^th week of gestation

• Iron storage – in liver.

  • At birth - Iron storage sufficient to last 4 to 6 months.

• Carbohydrate metabolism – initiation of feeds stabilizes blood glucose levels.

  • Colostrum contains high levels of glucose

Iron Storage

• in liver

  • At birth - Iron storage sufficient to last 4 to 6 months.

  • Preterm and SGA infants have lower iron stores; more likely to need iron supplementation

  • suck iron stores from mom, lasts for half a year

  • Superior bioavailability of iron in breast milk than in formula

  • Exclusive BF for 6 months is recommended (WHO)

  • Formula should contain supplemental iron

Trimester development

• first trimester - organs being develop

• second trimester: non viable fetus to viable

• third trimester: fully functioning human (but still immature); bulking and storage (take on extra weight; double in size)

Physiological Adaptions: Immune System

• Circulating Antibodies in newborn: Immunoglobulin IgG

  • Transported across placenta from maternal circulation (begins at 14 weeks gestation and is > during 3^rd trimester.

  • Key for immunity from bacteria and viruses

  • Passive immunity – antimicrobial protection during 1^st 3 months after birth

  • Infants have the ability to develop but have taken versions of immunity from mom 

    • if mom receives immunizations during pregnancy, can be passed through placenta to infant

  • BF does provide active immunity

IgM

fetus produces IgM by 8^th week gestation

• Important for immunity from blood borne pathogens

IgA

• membrane-protective

  • Missing from respiratory track, urinary tract & GI tract (unless breastfed)

  • In breast milk – neutralizes bacterial & viral pathogens in the intestines

  • Lessens risk of allergy & food intolerances

Risk for infections and Early Signs of Infection

• leading cause of morbidity & mortality

  • temp

  • hypothermia

  • lethargy

  • irritability

  • poor feeding

  • vomiting & diarrhea

Vernix caseosa 

• cheese-like whitish substance after 35 weeks

  • Contains sebaceous gland secretions

  • Emollient and antimicrobial properties preventing fluid loss through skin

  • Antioxidant properties

  • Leave vernix intact – decreases skin pH, decreases skin erythema, improves skin hydration

  • develops on their body that protects skin against fluid environment

Acrocyanosis

• when hands & feet are slightly cyanotic due to vasomotor instability

  • Normal over first 7-10 days

Lanugo

fine hair over face, shoulders and back

• protective mechanism; falls out within first few weeks

Eccymosis (bruising)

• edema of face due to face presentation, forceps-assisted birth,

  • vacuum extraction

  • d/t being pressed against pelvis and cervix 

Sweat glands

• newborns have sweat glands

• term infants do not sweat for first 24 hours.

Milia

small white sebaceous glands on newborn face

• “baby acne”

• dont pick, pop, etc.→can become open wound

• (not actually pimples as babies don't produce hormones)

Desquamation

peeling of skin of term newborn begins several days after birth

Physiological Adaptions: Integumentary System

• Babies have lots of skin issues

• Newborn rashes are very common - is it persistent or developing into something else 

• Creases on palms - Soles of feet should be assessed during 1^st few hours  for number of creases.

  • Note: more creases as skin dries.

  • Preterm infants – few creases if any

Mongolian Spots

• congenital birthmarks, bluish black areas of pigmentation over any part of exterior (back or buttocks) or body/extremities. 

•  freq in newborns whose ethnic origins are Mediterranean, latin America, Asia, Africa.

• Fade over months/years

Nevi

• Nevus Simplex (aka stork bites, angle kisses)

  • Flat, pink capillary hemangiomas; easily blanched

  • Fade in 1-2 years

  •  appear on upper eyelids, nose, upper lip, lower occiput bone and nape of neck.

Erythema Toxicum

• ransient newborn rash

  • 24 – 72 hrs. in term infants

• appear suddenly anywhere on body.

• Inflammatory response

• No tx

Physiological Adaptions: Reproductive System (Female)

• External genitalia (labia majora & minora may be edematous with pigmentation)

• All genders tend to have swollen genitalias b/c pumped w/ mom’s hormones

•  full complement of ova

• Note: preterm infants – clitoris is prominent, labia major small; more vernix caseosa

Pseudomenstruation

mucoid vaginal discharge with slight bloody spotting (increase in estrogen in pregnancy & drop at birth)

• not reproductive blood →moms hormones 

Physiological Adaptions: Reproductive System (Male)

• urethra at tip of penis (epispadias and hypospadias are congenital deformations)

• testes descend into scrotum by birth; tight prepuce (foreskin) is normal and may cover the urethral opening.

• Rugae appear on scrotum (28 – 36 weeks gestation); > 40 weeks – testes palpated in scrotum; rugae cover scrotal sac

• Scrotum has extra pigmentation due to maternal estrogen

Smegma

white cheesy substance found under foreskin

Epithelial pearls

seen on tip of the prepuce (keratinization in squamous cells)

Hydrocele

accumulation of fluid around testes that usually resolves without intervention

Swelling of breast tissue

• in any gender due to hyperestrogenism of pregnancy. May have thin discharge (witch’s milk)

  • Symmetrical nipples

  • Elevated areola; breast buds

Signs of reproductive system problems

• ambiguous genitalia

• fecal discharge from vagina (rectovaginal fistula)

• hypospadias or epispadias

Physiological adaptions: Skeletal System

• At birth, more cartilage than ossified bone

• Spine – vertebrae flat and straight. Assess for pilonidal dimple (associated with spina bifida)

• Extremities – symmetrical, equal in length, 5 fingers, 5 toes, nails

  • Developmental dysplasia of hip (DDH) is shallow hip socket where femur may slip out

• Arms longer than legs

Caput succedaneum

• edematous area of scalp (occiput) due to compression of vessels from pressure on cervix (slows venous return)

• slower venous return causes an increase in tissue fluids witin the skin of the scalp → leads to edematous swelling

  • Extends across suture lines of skull

  • Disappears in 3 -4 days.

Cephalhematoma

• collection of blood between skull bone and periosteum due to pressure against bony pelvis , low forceps, extraction

• does not cross suture lines

• Largest on 2^nd or 3^rd day

• Resolves in 3 – 6 weeks

  • As it resolves, the hemolysis of RBCs and may cause jaundice

Subgaleal hemorrhage

• bleeding into subgaleal compartment (loose connective tissue that connects frontal & occipital muscles and forms inner surface of scalp)

  • DIC – disseminated intravascular coagulation

    • More common in difficult vaginal births (vacuum extraction)

    • In extreme cases can lead to blood loss & hypovolemic shock, death

    • Assess for boggy scalp, pallor, increasing head circumference

Abnormal Extremeties

• oligodactyly (missing digits)

• polydactyly (extra digits)

• Syndactyly (fused fingers)

Newborn Head

• Head at term – ¼ of total body length.

• Cranial size and shape – distorted by moulding (shaping of fetal head through overlapping of cranial bones to facilitate movement through the birth canal

Physiological Adaptions:Neuromuscular system

• Newborn – vital, active, responsive, self-organized.

• Rapid growth of brain 

Brain requires glucose as a source of energy & large supply of oxygen for adequate metabolism.

• Observe closely for newborns at risk of hypoglycemia (diabetic moms, macrosomic , SGA

Tremors

• normal, associated with motions or voice

  • spontaneous motor activity may look like transient tremors of mouth and chin (during crying)

Newborn Reflexes

reflect maturity of newborn & developing nervous system

Physiological Adaptions: Behavioural Characteristics

•  behavioural & biological tasks for newborn development

  • Regulate physiological system (4 levels)

  • Expect infants to regulate themselves; anything outside is considered a variance

    • VS, pee/poo

Regulate physiological system: 4 weeks

1. Involuntary – HR, Resps, temp

2. Motor Organization – control random movements, muscle tone, reduce extra activity

3. State Regulation – ability to modulate consciousness

   • Develops predictable sleep and wake states

   • Able to react to stress (self-regulation & communication – crying and consolation)

4. Attention and Social Interaction – stay alert for longer periods; engage socially

Sleep-Wake states

unique characteristics of infant (teach parents about positive interactions and attachment)

Factors that influence behaviour of newborns

• Gestational age

• Stimuli- Responses to loud noises, stimuli, bright lights, monitor alarms

• Medication – effects of maternal analgesia during labour

  • Cause & effect relationship between epidurals and narcotics and BF behaviours

• expect infant to act according to age

• premature: lower coping skills, not great at feeding, more fussy and lower energy, less developed lungs

Vision

• incomplete structure of eyes, muscles immature

  • Accommodation at 3 months postpartum

  • Pupils reactive to light; blink reflex; sensitive to light

  • Term – see to distance of 50 cm, while clarity is 17 – 20 cm (distance from mom’s face to newborn’s face during BF)

  • Detect colour at 2 months; birth – 5 days  attracted to black and white patterns

  • Respond to light with movement

Hearing

• similar to adult once amniotic fluid drains from ears; react to noise with Moro (startle) reflex

•  hearing is essential for attachment (more important than vision)

Smell

• high sense of smell; react to strong odors (turn away), attracted to sweet smells

  • Can tell difference between mother and other lactating women

Taste

•  sweet solutions = eager sucking

• sour solutions = puckering of lips 

  • Non-nutritive sucking to relieve tension & nutritive sucking