[MOD16A - PHYSIO] Fetal and Neonatal Physiology_2028

What is the typical length of a full-term Filipino neonate at birth?

50 cm

During which trimester does fetal weight increase most significantly?

Third trimester

What is the typical birth weight of a Filipino neonate?

2.5-3 kg

What is the fetal weight at 20 weeks?

460 g

What is the fetal weight at 25 weeks?

1 kg

What is the weight threshold for neonatal viability?

500 g

At how many weeks are gross characteristics of all fetal organs already developing?

4 weeks

What developmental milestone occurs beyond 4 months of gestation?

Details of organs are established

At birth, which organs remain structurally immature?

Brain, kidney, and liver

When does the fetal heart begin beating?

4 weeks after fertilization

What is the fetal heart rate at 4 weeks?

65 bpm

What should the neonate's heart rate be immediately after birth?

>100 bpm

Where does mesoblastic hematopoiesis occur?

Yolk sac

What is the site of hematopoiesis starting at 6-8 weeks AOG?

Liver

When does the liver remain the predominant site of hematopoiesis?

Up to 20-24 weeks of gestation

Which organ takes over as the main hematopoietic site in the myeloid stage?

Bone marrow

What stimulates fetal respiratory movements by the end of the first trimester?

Fetal asphyxia and tactile stimuli

Why is respiration inhibited during the last trimester?

To prevent fluid and debris filling the lungs

What fetal organ secretes small amounts of clean fluid into the lungs before birth?

Alveolar epithelium

At what age does fetal swallowing and respiration begin?

16 weeks AOG

At what age does fetal hearing become more sensitive?

32 weeks

Which brain structures are fully myelinated by 1 year of age?

Some major tracts of the brain

Which part of the CNS is immature at birth and does not participate in function?

Cerebral cortex

By what age does a child have more neuronal connections than at birth?

2 years

Why should caregivers speak and interact with babies from birth to 2 years?

To support neuronal development

When does fetal amniotic fluid ingestion begin?

16 weeks

What causes the anus to relax and release meconium in utero?

Hypoxia

What condition results from inhalation of meconium-stained fluid?

Meconium aspiration syndrome

When does fetal urine production begin?

12-16 weeks AOG

What percentage of amniotic fluid is composed of fetal urine?

70-80%

What does polyhydramnios suggest should be evaluated?

Gastrointestinal tract

What system regulates fetal acid-base and fluid balance?

Placenta

By what age does renal function approximate that of an adult?

2 years

What is the main energy source for the fetus?

Glucose

When is half of fetal calcium and phosphate accumulation completed?

Last 4 weeks of gestation

When does fetal hemoglobin synthesis begin?

3rd week after fertilization

Where is about ⅓ of fetal iron stored?

Liver

Which vitamin is needed for red blood cell and CNS formation?

Vitamin B12 and folic acid

Which vitamin is needed for connective tissue and bone matrix?

Vitamin C

Which vitamin promotes fetal bone growth and calcium absorption?

Vitamin D

What condition results from early pregnancy Vitamin E deficiency?

Spontaneous abortion

Which vitamin is needed for synthesis of prothrombin and clotting factors?

Vitamin K

Why is vitamin K deficient in neonates?

Lack of colonic flora to produce it

What bleeding disorder results from vitamin K deficiency?

Acquired Prothrombin Complex Deficiency (APCD)

How quickly should a neonate breathe after birth?

Within seconds to 1 minute

What is the risk if breathing is delayed >10 minutes at birth?

Permanent brain impairment or death

What is the necessary pressure to open alveoli during the first breath?

More than 25 mmHg negative pressure

What pressure is commonly reached in the first inspiration of a normal neonate?

More than 60 mmHg

What substance assists in alveolar opening by reducing surface tension?

Surfactant

When do type II alveolar cells begin secreting surfactant?

Last 1-3 months of gestation

What gestational age has sufficient surfactant levels?

35 weeks AOG

What condition is characterized by proteinaceous fluid in alveoli and inadequate surfactant?

Respiratory Distress Syndrome (RDS) / Hyaline Membrane Disease

Why are infants of diabetic mothers at higher risk for RDS?

Insulin inhibits cortisol-induced surfactant production

Which fetal organ is nonfunctional before birth?

Lungs

What percentage of fetal cardiac output goes to the placenta?

55%

What happens to systemic vascular resistance after placenta removal?

It increases

What happens to pulmonary vascular resistance after lung expansion?

It decreases

What causes the foramen ovale to close functionally after birth?

Higher pressure in the left atrium than the right

What closes the ductus arteriosus functionally?

Constriction of its muscular wall within 1-8 days

What closes the ductus arteriosus anatomically?

Growth of fibrous tissue into its lumen over 1-4 months

What drug is used to treat patent ductus arteriosus?

Indomethacin

What closes the ductus venosus after birth?

Muscle wall contraction within 1-3 hours

How does portal venous pressure change after ductus venosus closure?

Rises from 0 to 6-10 mmHg

Before birth, what is the main glucose source for the fetus?

Maternal blood

After birth, why does neonatal blood glucose drop?

Inadequate gluconeogenesis due to immature liver

How low can neonatal glucose levels drop on the first day?

30-40 mg/dL

What is the typical percentage of physiologic weight loss in neonates?

5-10% (up to 20%)

What is the average normal respiratory rate of a neonate?

40 breaths per minute

How does functional residual capacity in neonates compare to adults?

Only half of adult value per body weight

What is the average blood volume of a newborn at birth?

300 mL

How much additional blood enters if umbilical cord remains attached briefly?

75 mL

What is average cardiac output in neonates?

500 mL/min

What is the arterial BP on the first day of life?

70/50 mmHg

What blood pressure is reached after the first month?

90/60 mmHg

What is the average neonatal WBC count?

~45,000/mm³

[T/F] WBC of 25,000-40,000/mm³ is abnormal in neonates.

FALSE. It is normal in neonates.

What is the plasma bilirubin level during the first 3 days of life?

Rises to ~5 mg/dL

What causes physiologic hyperbilirubinemia?

Immature liver conjugation of bilirubin

What is the cause of erythroblastosis fetalis?

Rh incompatibility between mother and fetus

Why are neonates prone to acidosis?

Twice the metabolic rate and immature kidneys

Why do neonates have poor thermoregulation?

Large body surface area relative to mass and immature control mechanisms

How long does it take for neonate body temperature to normalize after birth?

7-10 hours

Which antibodies are passed from mother to fetus before birth?

Gammaglobulins

By when do maternal antibodies drop below half in the neonate?

End of 1st month

Until what age do maternal antibodies offer protection against many infections?

About 6 months

Why is pertussis immunization required early?

Maternal antibodies against pertussis are insufficient

What condition causes milk secretion in neonates?

Hormonal effect of placental estrogens (witch's milk)

What endocrine condition causes low blood glucose in infants of diabetic mothers?

Hypertrophy of the islets of Langerhans

What maternal condition is associated with large babies?

Type 2 diabetes mellitus

What is cretin dwarfism caused by?

Congenital hypothyroidism

What causes retinopathy of prematurity?

Excessive oxygen therapy after birth

Why is ROP screening done in preterm babies?

Early detection prevents permanent blindness

What explains the need for incubators in premature infants?

Body temperature <35.5°C is linked to high mortality

What causes Cheyne-Stokes breathing in preterm infants?

Low functional residual capacity and immature brainstem control

Enumerate fetal lengths by age of gestation (at 12, 20, and 40 weeks).

12 weeks - 10 cm

20 weeks - 25 cm

40 weeks - 50-53 cm

Enumerate spontaneous movements by 10 weeks AOG.

Squinting

Mouth opening

Finger closure

Plantarflexion of toes

Enumerate the components of meconium.

Swallowed amniotic fluid

Mucus

Epithelial cells

Desquamated fetal cells

Lanugo

Scalp hair

Vernix

Debris and secretions

Enumerate causes of oligohydramnios.

Renal anomalies

Bladder outlet obstruction

What substrates are synthesized from glucose in the fetus?

Fats

Proteins

How much calcium and phosphate are accumulated in the fetus?

Calcium - 22.5 g

Phosphate - 13.5 g