OB: Chapter 17 Practice Questions

The nurse understands that closure of the foramen ovale occurs primarily due to which physiologic event after birth?

A. Decrease in oxygen tension in the lungs

B. Increase in left atrial pressure

C. Decrease in systemic vascular resistance

D. Increase in pulmonary vascular resistance

B. Increase in left atrial pressure

Why B is correct:

At birth the lungs expand, pulmonary blood flow increases, left atrial pressure rises above right atrial pressure. This pressure change pushes the septum primum against the septum secundum (functionally closing the foramen ovale). This is the primary physiologic mechanism for functional closure of the foramen ovale.

Why the others are incorrect:

A (Decrease in oxygen tension in the lungs): A decrease in pulmonary oxygen would not produce closure — increased oxygenation (not decrease) and increased pulmonary blood flow do.

C (Decrease in systemic vascular resistance): Systemic vascular resistance actually increases after cord clamping; a decrease would not drive left atrial pressure up relative to right.

D (Increase in pulmonary vascular resistance): Pulmonary vascular resistance falls after birth (not increases). An increase would reduce pulmonary blood flow and not favor closure.

A nurse caring for a term newborn notes oxygen saturation is 98% on room air. Which cardiovascular adaptation is most likely complete?

A. Closure of the ductus arteriosus

B. Reversal of blood flow through the ductus venosus

C. Conversion of the umbilical vein to a ligament

D. Opening of the foramen ovale

A. Closure of the ductus arteriosus

Why A is correct:

An SpO₂ of 98% on room air indicates good pulmonary gas exchange and high arterial oxygen tension. Increased oxygen tension is one of the major triggers for constriction and eventual closure of the ductus arteriosus. So when a newborn has normal-to-high oxygen saturation, it's likely the ductus arteriosus has functionally closed.

Why the others are incorrect:

B (Reversal of blood flow through the ductus venosus): The ductus venosus closure and changes in flow happen at cord clamping but "reversal of blood flow" is an odd phrase — the hallmark tied most directly to high SpO₂ is ductus arteriosus closure.

C (Conversion of the umbilical vein to a ligament): This occurs over days as vessels fibrose; SpO₂ doesn't directly show this conversion.

D (Opening of the foramen ovale): The foramen ovale does not open after birth; it functionally closes.

Which factor provides the strongest internal stimulus for initiating the newborn's first breath?

A. Decreased temperature and tactile stimulation

B. Increased PCO₂ and decreased pH

C. Sudden exposure to light and noise

D. Compression of the chest during birth

B. Increased PCO₂ and decreased pH

Why B is correct:

As the umbilical cord is clamped, fetal gas exchange via the placenta stops. CO₂ rises and pH falls (acidosis), stimulating central chemoreceptors in the medulla → this is a strong internal stimulus for initiating respiratory drive and the first breaths.

Why the others are incorrect:

A (Decreased temperature and tactile stimulation): Those are external stimuli (cold, touch) and important, but the question asked for the strongest internal stimulus.

C (Sudden exposure to light and noise): External sensory stimuli can help stimulate the newborn, but they are not the primary internal trigger.

D (Compression of the chest during birth): Chest compression and recoil assist initial lung inflation mechanically, but the strongest internal chemical stimulus is increased CO₂/decreased pH.

A nurse notices that a newborn's respiratory effort is weak immediately after delivery. Which factor most likely delayed the initiation of effective respirations?

A. High levels of catecholamines during birth

B. Persistent fluid in the alveoli

C. Cold stress exposure

D. Low carbon dioxide levels in the blood

B. Persistent fluid in the alveoli

Why B is correct:

If lung fluid is not cleared effectively (for example, in cesarean births without labor or with retained fluid), alveoli remain fluid-filled and gas exchange is impaired, making breaths weak or ineffective. This is a common mechanical cause of poor initial respirations.

Why the others are incorrect:

A (High levels of catecholamines during birth): Catecholamines actually help stimulate respiratory effort and surfactant release — they'd support respiration, not delay it.

C (Cold stress exposure): Cold usually increases respiratory effort (but can also cause respiratory compromise if severe). It's not the primary cause of weak initial effort.

D (Low carbon dioxide levels in the blood): Low CO₂ reduces respiratory drive; however, newborns usually have increased CO₂ after birth due to the cessation of placental gas exchange. Low CO₂ is not a typical cause of delayed initiation of breathing immediately after delivery.

Which newborn is at greatest risk for ineffective thermoregulation?

A. 40-week infant with flexed posture

B. 35-week infant with minimal brown fat

C. 39-week infant skin-to-skin with mother

D. 38-week infant recently breastfed

B. 35-week infant with minimal brown fat

Why B is correct:

Preterm infants (35 weeks) have less brown fat, less subcutaneous fat, thin skin, and immature thermoregulatory mechanisms — all increasing risk for heat loss and ineffective thermoregulation.

Why the others are incorrect:

A (40-week infant with flexed posture): Term infants with normal flexion conserve heat better — lower risk than preterm.

C (39-week infant skin-to-skin with mother): Skin-to-skin is an intervention that helps thermal stability — less risk.

D (38-week infant recently breastfed): Breastfeeding can help thermoregulation and is not a risk factor.

A nurse prevents conductive heat loss in a newborn by:

A. Keeping the crib away from air vents

B. Drying the infant immediately after birth

C. Placing the infant on a prewarmed radiant warmer

D. Covering the infant's head with a cap

C. Placing the infant on a prewarmed radiant warmer

Why C is correct:

Conduction is heat transfer through direct contact. If the infant is placed on a cold surface, heat is lost by conduction. A prewarmed radiant warmer provides a warm surface (prewarmed radiant bed) that prevents conductive heat loss by eliminating a cold contact surface.

Why the others are incorrect:

A (Keeping the crib away from air vents): That prevents convection losses (drafts) but not conduction specifically.

B (Drying the infant immediately): Drying prevents evaporative heat loss, not conduction.

D (Covering the infant's head with a cap): A cap reduces heat loss from the head (convection/evaporation), but it doesn't address conduction from the surface the infant lies on.

A nurse explains that brown adipose tissue is important for the newborn because it:

A. Provides energy for muscle contractions

B. Stores glycogen for glucose regulation

C. Generates heat through nonshivering thermogenesis

D. Serves as a reserve for water and electrolytes

C. Generates heat through nonshivering thermogenesis

Why C is correct:

Brown adipose tissue (brown fat) contains many mitochondria and vasculature and produces heat by metabolizing fatty acids — a process called nonshivering thermogenesis. This is critical in newborns who cannot shiver effectively.

Why the others are incorrect:

A (Provides energy for muscle contractions): Brown fat's primary role isn't muscle energy.

B (Stores glycogen for glucose regulation): Glycogen is stored in liver/muscle, not primarily in brown fat.

D (Serves as a reserve for water and electrolytes): Brown fat is not a water/electrolyte reserve.

Which finding would indicate normal hepatic adaptation in a newborn?

A. Passage of meconium within the first 48 hours

B. Jaundice within the first 12 hours of life

C. Blood glucose of 30 mg/dL at 6 hours old

D. Pale, clay-colored stools by day 3

A. Passage of meconium within the first 48 hours

Why A is correct:

Passing meconium early (usually within the first 24-48 hours) demonstrates an intact GI tract and successful transition to enteric function; it's a sign of normal neonatal gastrointestinal/hepatic adaptation.

Why the others are incorrect:

B (Jaundice within the first 12 hours of life): Early jaundice (<24 hours) is usually pathologic (e.g., hemolysis, ABO incompatibility) and is not a normal adaptation.

C (Blood glucose of 30 mg/dL at 6 hours old): That value indicates hypoglycemia (thresholds vary slightly, but 30 mg/dL is low for a stable term newborn) — abnormal.

D (Pale, clay-colored stools by day 3): Clay-colored stools suggest impaired bile excretion (cholestasis/biliary atresia) — abnormal.

A newborn at 3 days old has soft green-brown stools. The nurse interprets this as:

A. Meconium

B. Transitional stool

C. Milk stool

D. Steatorrhea

B. Transitional stool

Why B is correct:

By days 2-3 newborn stools progress from meconium (sticky, black-green) to transitional stools (soft green-black → green-brown) as intestinal contents and milk intake increase. At day 3 a soft green-brown stool is expected transitional stool.

Why the others are incorrect:

A (Meconium): Meconium is typical on day 1 and may pass into day 2 but by day 3 stools are usually transitional.

C (Milk stool): Milk stools typically appear by day 4-5 (yellow, seedy in breastfed babies).

D (Steatorrhea): Steatorrhea is fatty, foul-smelling stools and not a normal transitional pattern.

A nurse would expect which stool characteristics in a healthy breastfed newborn at day 5?

A. Firm, yellow-green with a foul odor

B. Loose, yellow-gold, and sour-smelling

C. Hard, brown, and formed

D. Soft, tan, and odorless

B. Loose, yellow-gold, and sour-smelling

Why B is correct:

Healthy breastfed newborn stools by about day 5 are classically loose, yellow-gold, often "seedy" or stringy and may have a sour/acidic smell. This is normal for breastfed infants.

Why the others are incorrect:

A (Firm, yellow-green with a foul odor): Formula-fed stools are more formed and have a different odor; "firm" is not typical for breastfed stools by day 5.

C (Hard, brown, and formed): That would be abnormal — maybe constipation or delayed feeding.

D (Soft, tan, and odorless): Not a typical description for healthy breastfed stool; breastfed stools have a distinctive yellow/gold and sour smell.

Which statement best describes the newborn's renal function during the first few days of life?

A. The newborn readily excretes excess sodium and water.

B. Urine output is minimal due to renal immaturity.

C. The kidneys have a high glomerular filtration rate.

D. The newborn efficiently metabolizes medications.

B. Urine output is minimal due to renal immaturity.

Why B is correct:

Newborn kidneys (especially in the first days) have a low glomerular filtration rate (GFR) and limited concentrating ability. Therefore urine output may be low initially and renal excretory function is immature.

Why the others are incorrect:

A (Newborn readily excretes excess sodium and water): Actually they have difficulty excreting sodium and handling fluid loads due to immature renal function.

C (The kidneys have a high glomerular filtration rate): No — neonates have a low GFR compared with older infants and adults.

D (The newborn efficiently metabolizes medications): Renal drug excretion and drug handling are immature, so many drugs require dosing adjustments — not efficient.

A nurse documents that a newborn has voided twice in the first 24 hours. The best nursing action is to:

A. Encourage more frequent feedings

B. Notify the healthcare provider immediately

C. Restrict fluids to avoid overload

D. Begin phototherapy for dehydration

A. Encourage more frequent feedings

Why A is correct:

Voiding only twice in the first 24 hours can be expected (urine output increases over the first days). Encouraging feeding supports hydration and increases urine output. This is a supportive nursing measure consistent with normal neonatal transition.

Why the others are incorrect:

B (Notify the healthcare provider immediately): Not indicated for only two voids in the first 24 hours unless other concerning signs (dehydration, poor perfusion) are present.

C (Restrict fluids to avoid overload): Newborns should not have fluids restricted in this situation; restricting would worsen hydration.

D (Begin phototherapy for dehydration): Phototherapy is used for hyperbilirubinemia, not dehydration. Also phototherapy doesn't treat low urine output.

During the first period of reactivity, the nurse expects the newborn to display which behavior?

A. Deep sleep with minimal response to stimuli

B. Irregular respirations, alertness, and rooting

C. Stable vital signs and relaxed muscle tone

D. Diminished reflexes and sluggish movements

B. Irregular respirations, alertness, and rooting

Why B is correct:

The first period of reactivity (birth → up to 30-120 minutes) is characterized by alertness, movement, strong reflexes such as rooting and sucking, and often irregular respirations. This is when infants are often receptive to early breastfeeding and bonding.

Why the others are incorrect:

A (Deep sleep with minimal response): That describes the period of decreased responsiveness (sleep phase), not the first period.

C (Stable vital signs and relaxed muscle tone): During first reactivity the infant is often active and vital signs can be somewhat variable.

D (Diminished reflexes and sluggish movements): That's not typical of the first reactive period — instead the newborn is quite responsive.

A nurse notices that a newborn is quiet and difficult to arouse 90 minutes after birth. Which phase of reactivity is the newborn likely in?

A. First period of reactivity

B. Period of decreased responsiveness

C. Second period of reactivity

D. Transition to extrauterine life

B. Period of decreased responsiveness

Why B is correct:

The period of decreased responsiveness (roughly 30-120 minutes after birth) is a sleep phase where the newborn is harder to arouse, shows decreased motor activity, and has lower responsiveness to external stimuli.

Why the others are incorrect:

A (First period of reactivity): That occurs immediately after birth and is when the infant is alert and active.

C (Second period of reactivity): Occurs later (about 2-8 hours after birth) where the infant reawakens and shows renewed interest.

D (Transition to extrauterine life): This is a general phrase; the specific phase described (quiet, hard to arouse at 90 minutes) best matches the period of decreased responsiveness.

A nurse is monitoring a newborn 5 hours after birth. The infant becomes alert and begins to suck vigorously. The nurse interprets this as:

A. The first period of reactivity

B. The period of decreased responsiveness

C. The second period of reactivity

D. A sign of hypoglycemia

C. The second period of reactivity

Why C is correct:

The second period of reactivity usually occurs about 2-8 hours after birth. It's when the newborn awakens from the earlier sleep period and often exhibits increased muscle tone, alertness, and rooting/sucking behavior — perfect timing for starting effective breastfeeding again.

Why the others are incorrect:

A (First period of reactivity): That is immediate after birth (0-30-120 minutes) and would have occurred earlier.

B (Period of decreased responsiveness): That is the sleeping period between the first and second reactivity — the infant would be less responsive, not suddenly vigorous at 5 hours.

D (A sign of hypoglycemia): While hypoglycemia can cause poor feeding or jitteriness, a vigorous suck at 5 hours is more consistent with normal second reactivity than hypoglycemia.

Which newborn assessment finding should the nurse report to the healthcare provider?

A. Hematocrit of 60%

B. Hemoglobin of 18 g/dL

C. Platelet count of 90,000/µL

D. White blood cell count of 22,000/µL

C. Platelet count of 90,000/µL

Why C is correct:

A platelet count of 90,000/µL in a newborn is thrombocytopenia (low). The range given in your notes was 100,000-300,000 (and many references use 150,000 as a standard cutoff). Regardless, 90,000 is below the normal neonatal range and could increase bleeding risk — it should be reported and evaluated.

Why the others are incorrect:

A (Hematocrit of 60%): Neonatal hematocrits are higher than adults; 52-63% is listed as normal in your notes, so 60% is within range.

B (Hemoglobin of 18 g/dL): Neonatal hemoglobin ranges around 17-20 g/dL per your notes — 18 is normal.

D (White blood cell count of 22,000/µL): WBC counts in newborns are higher than adults; 10,000-30,000 was listed as typical in your notes, so 22,000 is within expectation.

Which physiologic change contributes most to the closure of the ductus arteriosus after birth?

A. Increased prostaglandin levels

B. Decreased oxygen saturation

C. Increased oxygenation of the blood

D. Elevated systemic pressure in the right atrium

C. Increased oxygenation of the blood

Why C is correct:

After birth, increased oxygen tension in arterial blood causes the smooth muscle in the ductus arteriosus to constrict, initiating functional closure. Oxygen acts as a potent vasoconstrictor of the ductus arteriosus.

Why the others are incorrect:

A (Increased prostaglandin levels): Prostaglandins (especially PGE₂) keep the ductus arteriosus open. An increase would oppose closure.

B (Decreased oxygen saturation): Low oxygen keeps the ductus arteriosus patent; decreased saturation would prevent closure.

D (Elevated systemic pressure in the right atrium): Right atrial pressure doesn't typically drive ductus closure; rather, pulmonary blood flow/oxygen and falling prostaglandins do.

A nurse caring for a newborn observes that the baby's temperature is dropping. Which condition is the nurse most concerned about developing next?

A. Hypoglycemia

B. Hypertension

C. Hyperbilirubinemia

D. Polycythemia

A. Hypoglycemia

Why A is correct:

Cold stress increases metabolic demand and oxygen consumption and causes increased utilization of glycogen and glucose to generate heat (through brown fat metabolism). This can rapidly deplete newborn glucose stores and lead to hypoglycemia — a common and immediate concern when infants become cold.

Why the others are incorrect:

B (Hypertension): Hypothermia/hypothermia-related stress more commonly affects glucose, oxygenation and can cause bradycardia, not hypertension primarily.

C (Hyperbilirubinemia): Cold stress may contribute indirectly to later hyperbilirubinemia (as poor feeding → dehydration/insufficient stooling → increased enterohepatic circulation), but hypoglycemia is the more immediate concern.

D (Polycythemia): Polycythemia is related to chronic fetal hypoxia or maternal issues, not an immediate consequence of dropping temperature.

A newborn delivered by cesarean section is more likely to experience which transition challenge?

A. Hypothermia due to evaporation

B. Delayed fluid clearance from the lungs

C. Excessive bilirubin conjugation

D. Increased urine output after birth

B. Delayed fluid clearance from the lungs

Why B is correct:

Labor and vaginal birth mechanically compress the thorax and help expel fetal lung fluid; they also stimulate catecholamine release that promotes fluid absorption. Cesarean delivery (especially without labor) often results in less thoracic squeeze and less catecholamine surge, so these infants may retain more lung fluid longer → risk transient tachypnea of the newborn and delayed respiratory adaptation.

Why the others are incorrect:

A (Hypothermia due to evaporation): While hypothermia can occur in any delivery mode, the chest compression / lung fluid issue is a classic respiratory transition challenge linked to cesarean section.

C (Excessive bilirubin conjugation): Cesarean delivery isn't associated with increased bilirubin conjugation — if anything, delayed feeding could predispose to hyperbilirubinemia, but that's not the classic immediate challenge.

D (Increased urine output after birth): Cesarean delivery does not cause increased urine output; if anything, fluid shifts vary but increased output is not the classic problem.

A nurse is caring for a preterm newborn. Which statement best explains why this infant is more prone to cold stress?

A. Preterm infants have increased glycogen reserves.

B. Preterm infants produce more brown fat than term infants.

C. Preterm infants lack sufficient brown adipose tissue.

D. Preterm infants maintain temperature through shivering.

C. Preterm infants lack sufficient brown adipose tissue.

Why C is correct:

Brown adipose tissue accumulates in late gestation; preterm infants have markedly less brown fat and less subcutaneous fat. Without adequate brown fat they cannot perform nonshivering thermogenesis effectively and are therefore much more prone to cold stress.

Why the others are incorrect:

A (Preterm infants have increased glycogen reserves): They actually have fewer glycogen and fat reserves.

B (Preterm infants produce more brown fat than term infants): Opposite — they have less.

D (Preterm infants maintain temperature through shivering): Newborns (especially preterms) do not shiver effectively; shivering is not a primary neonatal thermoregulatory mechanism.