Transition from Fetal to Neonatal Circulation, and Newborn Anatomy and Physiology Practice Questions

25 multiple-choice questions on Transition from fetal to neonatal circulation, and newborn anatomy and physiology for paramedic and EMT students, from Chapter 43 (Neonatal Care). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. In the fetus, the ductus venosus carries oxygenated blood from the umbilical vein so that most of it bypasses the:

   1. A. Lungs
   2. B. Kidneys
   3. C. Liver
   4. D. Right atrium
   Show answer

   Answer: C. Liver

   The ductus venosus shunts umbilical venous blood past the liver into the inferior vena cava. The lungs are bypassed by two other shunts, the foramen ovale and the ductus arteriosus, not by the ductus venosus.

2. The fetal structure that lets blood flow directly from the right atrium to the left atrium is the:

   1. A. Ductus arteriosus
   2. B. Ductus venosus
   3. C. Umbilical artery
   4. D. Foramen ovale
   Show answer

   Answer: D. Foramen ovale

   The foramen ovale is an opening in the atrial septum that sends oxygen-rich blood straight to the left heart. The ductus arteriosus also bypasses the lungs, but it connects the pulmonary artery to the aorta, not the two atria.

3. Before birth, the ductus arteriosus carries most of the blood leaving the right ventricle from the:

   1. A. Aorta to the pulmonary artery
   2. B. Pulmonary artery to the aorta
   3. C. Right atrium to the left atrium
   4. D. Umbilical vein to the vena cava
   Show answer

   Answer: B. Pulmonary artery to the aorta

   Fetal pulmonary vascular resistance is high, so right ventricular output takes the low-resistance path through the ductus arteriosus into the aorta. Flow from the aorta into the pulmonary artery occurs only after birth, when resistances reverse, and is what keeps a patent ductus symptomatic.

4. The key event that starts the change from fetal to newborn circulation is:

   1. A. Lung expansion with the first breaths
   2. B. Delivery of the placenta after the birth
   3. C. The first newborn feeding
   4. D. Closure of the ductus venosus
   Show answer

   Answer: A. Lung expansion with the first breaths

   Air entering the alveoli and the rise in oxygen relax the pulmonary arterioles, so pulmonary vascular resistance falls sharply and blood flows to the lungs. Delivery of the placenta follows the birth and does not drive the circulatory change in the infant.

5. After the first breaths, the foramen ovale functionally closes mainly because:

   1. A. Oxygen constricts the atrial septum
   2. B. Right atrial pressure rises above left
   3. C. Left atrial pressure rises above right
   4. D. The ductus arteriosus pulls it shut
   Show answer

   Answer: C. Left atrial pressure rises above right

   Increased pulmonary blood flow returns to the left atrium and raises its pressure, pressing the flap of the foramen ovale closed. If right-sided pressure stayed higher, as in pulmonary hypertension, the shunt would remain open and the infant would stay cyanotic.

6. The ductus arteriosus normally begins to constrict in the hours after birth in response to:

   1. A. A rising blood oxygen level
   2. B. A falling blood oxygen level
   3. C. A rising blood glucose level
   4. D. Clamping of the umbilical vein
   Show answer

   Answer: A. A rising blood oxygen level

   Higher arterial oxygen and falling prostaglandin levels make the ductal muscle contract. Hypoxia and acidosis do the opposite and keep the ductus open, which is why a hypoxic newborn can slip back toward fetal circulation.

7. A newborn who remains hypoxic and acidotic after birth is at risk for persistent pulmonary hypertension, meaning:

   1. A. The foramen ovale closes too quickly
   2. B. Fetal shunting continues past the lungs
   3. C. Blood pressure is too high for the age
   4. D. The ductus venosus reopens in the liver
   Show answer

   Answer: B. Fetal shunting continues past the lungs

   Hypoxia and acidosis keep pulmonary arterioles constricted, so blood continues to bypass the lungs through the foramen ovale and ductus arteriosus. The result is profound cyanosis; it is a failure of the shunts to close, not premature closure.

8. A 5-week-old was born at home, and the parents declined the newborn vitamin K shot. She is now lethargic, vomiting, and has a bulging fontanelle. You should suspect:

   1. A. Meningitis from a bacterial infection in the home
   2. B. Shaken baby injury, since bleeding cannot occur on its own
   3. C. Dehydration from vomiting and poor feeding
   4. D. Bleeding in the brain from low clotting factors
   Show answer

   Answer: D. Bleeding in the brain from low clotting factors

   Newborns have low levels of vitamin K-dependent clotting factors, and breast milk contains little vitamin K. Without the birth injection, vitamin K deficiency bleeding can occur weeks later, often as a brain bleed. Abuse and meningitis must still be considered, but dehydration produces a sunken, not bulging, fontanelle.

9. In the textbook, the term neonate refers to an infant from birth to about:

   1. A. 28 days of age
   2. B. 7 days of age
   3. C. 6 months of age
   4. D. 1 year of age
   Show answer

   Answer: A. 28 days of age

   The neonatal period covers the first 28 days, or first month, of life; newly born describes the first minutes to hours. One year is the upper limit of infancy, not of the neonatal period.

10. Most newly born infants need no help beyond drying and warming. About what share require some assistance to begin breathing?

    1. A. About 1%
    2. B. About 10%
    3. C. About 30%
    4. D. About 50%
    Show answer

    Answer: B. About 10%

    Roughly 10% of newborns need some help to start breathing, and fewer than 1% need extensive resuscitation such as compressions or drugs. Reading 1% as the share needing any help confuses minimal support with full resuscitation.

11. A well-appearing 3-day-old feeding normally has mild yellow skin that began on day 2. The most likely cause is:

    1. A. A blocked bile duct needing emergency surgery
    2. B. Hepatitis passed from the mother at delivery
    3. C. Breakdown of extra red cells by a young liver
    4. D. Carotene from the mother's diet in breast milk
    Show answer

    Answer: C. Breakdown of extra red cells by a young liver

    Physiologic jaundice appears after the first day as the newborn breaks down its extra fetal red cells faster than its immature liver can process the bilirubin. It peaks around days 3 to 5. Jaundice in the first 24 hours, or in an infant who looks ill, is not physiologic and needs prompt evaluation.

12. Compared with an adult, a newborn's head is proportionally large. When the infant lies supine on a flat surface, this tends to:

    1. A. Extend the neck and open the airway
    2. B. Push the tongue away from the airway
    3. C. Have no effect on airway position
    4. D. Flex the neck and kink the airway
    Show answer

    Answer: D. Flex the neck and kink the airway

    The large occiput flexes the neck forward and can obstruct the narrow airway. A thin towel under the shoulders brings the head to the neutral sniffing position; overextension is avoided because it can also kink the soft trachea.

13. After a long vaginal delivery, a newborn's head looks elongated and pointed, with ridges where the skull bones overlap. The baby is active and feeding. You should:

    1. A. Suspect a depressed skull fracture and immobilize
    2. B. Apply gentle pressure to reshape the skull
    3. C. Transport urgently for a suspected brain bleed
    4. D. Reassure the parents that this is normal molding
    Show answer

    Answer: D. Reassure the parents that this is normal molding

    During birth the unfused skull bones slide over one another so the head can pass through the pelvis. This molding resolves over a few days. Pressing on the skull is harmful, and an active, feeding infant does not need emergency imaging for normal molding.

14. A 7-day-old has redness spreading 2 cm around the umbilical stump, a foul-smelling discharge, and poor feeding. The best interpretation is:

    1. A. Normal healing that needs dry cord care at home
    2. B. An infection of the stump needing urgent care
    3. C. A hernia that should be gently pushed back in
    4. D. An allergy to the cord clamp that will fade
    Show answer

    Answer: B. An infection of the stump needing urgent care

    Spreading redness, foul drainage, and a sick-appearing infant point to omphalitis, an infection of the umbilical stump that can spread into the abdominal wall and bloodstream within hours. A normal stump dries and falls off without spreading redness. This infant needs transport for IV antibiotics.

15. A newborn produces heat mainly through nonshivering thermogenesis, which:

    1. A. Uses muscle tremor to make heat
    2. B. Burns white fat stored under the skin
    3. C. Burns brown fat and uses more oxygen
    4. D. Works best in preterm infants
    Show answer

    Answer: C. Burns brown fat and uses more oxygen

    Brown fat metabolism generates heat but raises oxygen and glucose consumption, so a cold infant can become hypoxic, hypoglycemic, and acidotic. The heat comes from brown fat around the neck, back, and kidneys rather than from ordinary white fat, and preterm infants have much less of it, so they cool faster. Muscle tremor is shivering, which newborns cannot do effectively.

16. At 30 minutes of age, a term newborn at rest is breathing 74 times per minute with mild retractions. You should interpret this rate as:

    1. A. Tachypnea that signals respiratory distress
    2. B. A normal rate for the first hour of life
    3. C. Bradypnea that needs ventilation at once
    4. D. A normal response to drying and stimulation
    Show answer

    Answer: A. Tachypnea that signals respiratory distress

    Normal newborn breathing is 30 to 60 breaths/min, so a sustained resting rate above 60 with retractions is tachypnea and a sign of distress that needs monitoring and pulse oximetry. Newborns breathe faster than older children, but not this fast at rest.

17. Normal heart rate for a healthy newborn is roughly:

    1. A. 120 to 160 beats/min
    2. B. 60 to 100 beats/min
    3. C. 40 to 60 beats/min
    4. D. 180 to 220 beats/min
    Show answer

    Answer: A. 120 to 160 beats/min

    A healthy newborn at rest usually has a heart rate of about 120 to 160 beats/min. Published ranges vary somewhat, and crying can briefly push a healthy infant higher, but a rate below 100 calls for positive-pressure ventilation and a rate below 60 despite good ventilation calls for compressions. Sixty to 100 and 40 to 60 are bradycardic ranges that need intervention, not normal values. A sustained resting rate of 180 to 220 suggests a tachydysrhythmia such as SVT, or fever or shock. (NRP 9th ed. heart rate thresholds; Caroline.)

18. A full-term newborn's circulating blood volume is approximately:

    1. A. 45 to 50 mL/kg, about 150 mL
    2. B. 85 to 90 mL/kg, about 300 mL
    3. C. 120 mL/kg, about 450 mL
    4. D. 70 mL/kg, about 600 mL
    Show answer

    Answer: B. 85 to 90 mL/kg, about 300 mL

    A 3.5-kg term infant has only about 300 mL of blood, so a loss of 30 to 60 mL from a cord or other bleed is significant. Six hundred milliliters would be the volume of a much larger child.

19. Most of a newborn's hemoglobin is fetal hemoglobin. Compared with adult hemoglobin, fetal hemoglobin:

    1. A. Binds oxygen more loosely
    2. B. Carries less oxygen per gram
    3. C. Is gone within a week
    4. D. Binds oxygen more tightly
    Show answer

    Answer: D. Binds oxygen more tightly

    Fetal hemoglobin has a higher affinity for oxygen, which let the fetus take up oxygen from maternal blood at low partial pressures, and it is gradually replaced over the first months rather than within a week. Each gram carries about the same amount of oxygen when fully saturated; the difference is in affinity. Looser binding describes adult hemoglobin relative to fetal hemoglobin, the reverse of the truth.

20. You check a 2-minute-old newborn and note blue hands and feet, a pink trunk and lips, a strong cry, and a heart rate of 150 beats/min. You should:

    1. A. Begin blow-by oxygen at once
    2. B. Start positive-pressure ventilation
    3. C. Recognize normal acrocyanosis
    4. D. Suspect cyanotic heart disease
    Show answer

    Answer: C. Recognize normal acrocyanosis

    Peripheral cyanosis of the hands and feet is common in the first hours and is not treated when the core is pink and vital signs are normal. Blow-by oxygen is reserved for central cyanosis or low preductal saturation, not acrocyanosis.

21. A newborn's blood glucose falls in the first hours of life mainly because:

    1. A. Insulin from the placenta keeps acting
    2. B. The maternal glucose supply has stopped
    3. C. The liver cannot store any glycogen
    4. D. Breast milk lowers the glucose level
    Show answer

    Answer: B. The maternal glucose supply has stopped

    Once the cord is cut, the infant must rely on limited glycogen stores and feeding to maintain glucose, so stress, cold, or prematurity can rapidly cause hypoglycemia. Maternal insulin does not cross the placenta; fetal hyperinsulinism in diabetic pregnancies is the infant's own insulin.

22. You are assessing a newly born infant's heart rate during the first minute. Which method is most accurate in the field when it is available?

    1. A. Palpating the base of the umbilical cord
    2. B. Pulse oximetry on the right hand
    3. C. A cardiac monitor with chest leads
    4. D. Palpating the brachial pulse
    Show answer

    Answer: C. A cardiac monitor with chest leads

    Current guidelines prefer an ECG monitor for an accurate heart rate in a newborn needing resuscitation, with auscultation as the quick alternative. Pulse oximetry takes time to pick up a signal and can read low or drop out in the first minutes, and peripheral pulses such as the brachial are hard to feel in a newborn. Palpating the cord is fast but tends to underestimate the rate and can prompt unneeded interventions.

23. A newborn's trachea is short and narrow. During ventilation and intubation, this means:

    1. A. Small head movements can displace a tube
    2. B. Larger tubes are easier to pass and secure
    3. C. Hyperextension improves the airway
    4. D. Cricoid pressure is routinely needed
    Show answer

    Answer: A. Small head movements can displace a tube

    A short trachea means only a small distance separates a tube in the trachea from one in a mainstem bronchus or out of the cords, so the head must be kept in position and placement rechecked after every move. Hyperextension narrows the soft trachea rather than improving it.

24. A newborn's skin is red, thin, and covered in places with a white, cheesy coating. This coating is:

    1. A. Lanugo, a sign that the infant is postterm
    2. B. Meconium, a sign of fetal distress
    3. C. Milia, a sign of infection
    4. D. Vernix caseosa, which protects the skin
    Show answer

    Answer: D. Vernix caseosa, which protects the skin

    Vernix is a normal protective coating, more abundant in preterm and term infants and reduced in postterm infants. Lanugo is fine body hair seen mostly in preterm newborns, not a cheesy coating.

25. Newborns have immature kidneys and liver. In drug dosing, this means a newborn:

    1. A. Needs adult doses scaled by age
    2. B. Eliminates drugs faster than adults
    3. C. Clears many drugs more slowly
    4. D. Cannot be given any IV medications
    Show answer

    Answer: C. Clears many drugs more slowly

    Immature hepatic and renal function prolong the action of many drugs, so neonatal doses are weight based and often given at longer intervals. Faster elimination is the opposite of neonatal physiology.