Chapter 22: Physiologic and Behavioral Adaptations of the Newborn

12. A client is warm and asks for a fan in her room for her comfort. The nurse enters the room to assess the mother and her infant and finds the infant unwrapped in his crib with the fan blowing over him on "high." The nurse instructs the mother that the fan should not be directed toward the newborn and the newborn should be wrapped in a blanket. The mother asks why. The nurse's best response is: a. "Your baby may lose heat by convection, which means that he will lose heat from his body to the cooler ambient air. You should keep him wrapped and prevent cool air from blowing on him." b. "Your baby may lose heat by conduction, which means that he will lose heat from his body to the cooler ambient air. You should keep him wrapped and prevent cool air from blowing on him." c. "Your baby may lose heat by evaporation, which means that he will lose heat from his body to the cooler ambient air. You should keep him wrapped and prevent cool air from blowing on him." d. "Your baby will get cold stressed easily and needs to be bundled up at all times."

ANS: A "Your baby may lose heat by convection, which means that he will lose heat from his body to the cooler ambient air. You should keep him wrapped and prevent cool air from blowing on him" is an accurate statement. Conduction is the loss of heat from the body surface to cooler surfaces, not air, in direct contact with the newborn. Evaporation is loss of heat that occurs when a liquid is converted into a vapor. In the newborn heat loss by evaporation occurs as a result of vaporization of moisture from the skin. Cold stress may occur from excessive heat loss, but this does not imply that the infant will become stressed if not bundled at all times. Furthermore, excessive bundling may result in a rise in the infant's temperature.

20. As related to the normal functioning of the renal system in newborns, nurses should be aware that: a. The pediatrician should be notified if the newborn has not voided in 24 hours. b. Breastfed infants likely will void more often during the first days after birth. c. "Brick dust" or blood on a diaper is always cause to notify the physician. d. Weight loss from fluid loss and other normal factors should be made up in 4 to 7 days.

ANS: A A newborn who has not voided in 24 hours may have any of a number of problems, some of which deserve the attention of the pediatrician. Formula-fed infants tend to void more frequently in the first 3 days; breastfed infants void less during this time because the mother's breast milk has not come in yet. Brick dust may be uric acid crystals; blood spotting could be caused by withdrawal of maternal hormones (pseudomenstruation) or a circumcision. The physician must be notified only if there is no apparent cause of bleeding. Weight loss from fluid loss may take 14 days to regain.

7. A new mother states that her infant must be cold because the baby's hands and feet are blue. The nurse explains that this is a common and temporary condition called: a. Acrocyanosis. c. Harlequin color. b. Erythema neonatorum. d. Vernix caseosa.

ANS: A Acrocyanosis, or the appearance of slightly cyanotic hands and feet, is caused by vasomotor instability, capillary stasis, and a high hemoglobin level. Acrocyanosis is normal and appears intermittently over the first 7 to 10 days. Erythema toxicum (also called erythema neonatorum) is a transient newborn rash that resembles flea bites. The harlequin sign is a benign, transient color change in newborns. Half of the body is pale, and the other half is ruddy or bluish red with a line of demarcation. Vernix caseosa is a cheeselike, whitish substance that serves as a protective covering.

34. The nurse should immediately alert the physician when: a. The infant is dusky and turns cyanotic when crying. b. Acrocyanosis is present at age 1 hour. c. The infant's blood glucose level is 45 mg/dL. d. The infant goes into a deep sleep at age 1 hour.

ANS: A An infant who is dusky and becomes cyanotic when crying is showing poor adaptation to extrauterine life. Acrocyanosis is an expected finding during the early neonatal life. This is within normal range for a newborn. Infants enter the period of deep sleep when they are about 1 hour old.

31. Nurses can prevent evaporative heat loss in the newborn by: a. Drying the baby after birth and wrapping the baby in a dry blanket. b. Keeping the baby out of drafts and away from air conditioners. c. Placing the baby away from the outside wall and the windows. d. Warming the stethoscope and the nurse's hands before touching the baby.

ANS: A Because the infant is wet with amniotic fluid and blood, heat loss by evaporation occurs quickly.Heat loss by convection occurs when drafts come from open doors and air currents created by people moving around. If the heat loss is caused by placing the baby near cold surfaces or equipment, it is referred to as a radiation heat loss. Conduction heat loss occurs when the baby comes in contact with cold objects or surfaces.

29. A collection of blood between the skull bone and its periosteum is known as a cephalhematoma. To reassure the new parents whose infant develops such a soft bulge, it is important that the nurse be aware that this condition: a. May occur with spontaneous vaginal birth. b. Happens only as the result of a forceps or vacuum delivery. c. Is present immediately after birth. d. Will gradually absorb over the first few months of life.

ANS: A Bleeding may occur during a spontaneous vaginal delivery as a result of the pressure against the maternal bony pelvis. The soft, irreducible fullness does not pulsate or bulge when the infant cries. Low forceps and other difficult extractions may result in bleeding. However, cephalhematomas can also occur spontaneously. The swelling may appear unilaterally or bilaterally and is usually minimal or absent at birth. It increases over the first 2 to 3 days of life. Cephalhematomas disappear gradually over 2 to 3 weeks. A less common condition results in calcification of the hematoma, which may persist for months.

2. Part of the health assessment of a newborn is observing the infant's breathing pattern. A full-term newborn's breathing pattern is predominantly: a. Abdominal with synchronous chest movements. b. Chest breathing with nasal flaring. c. Diaphragmatic with chest retraction. d. Deep with a regular rhythm.

ANS: A In normal infant respiration the chest and abdomen rise synchronously, and breaths are shallow and irregular. Breathing with nasal flaring is a sign of respiratory distress. Diaphragmatic breathing with chest retraction is a sign of respiratory distress. Infant breaths are not deep with a regular rhythm.

39. Which newborn reflex is elicited by stroking the lateral sole of the infant's foot from the heel to the ball of the foot? a. Babinski c. Stepping b. Tonic neck d. Plantar grasp

ANS: A The Babinski reflex causes the toes to flare outward and the big toe to dorsiflex. The tonic neck reflex (also called the fencing reflex) refers to the posture assumed by newborns when in a supine position. The stepping reflex occurs when infants are held upright with their heel touching a solid surface and the infant appears to be walking. Plantar grasp reflex is similar to the palmar grasp reflex: when the area below the toes is touched, the infant's toes curl over the nurse's finger.

40. Infants in whom cephalhematomas develop are at increased risk for: a. Infection. c. Caput succedaneum. b. Jaundice. d. Erythema toxicum.

ANS: B Cephalhematomas are characterized by bleeding between the bone and its covering, the periosteum. Because of the breakdown of the red blood cells within a hematoma, the infants are at greater risk for jaundice. Cephalhematomas do not increase the risk for infections. Caput is an edematous area on the head from pressure against the cervix.

14. The transition period between intrauterine and extrauterine existence for the newborn: a. Consists of four phases, two reactive and two of decreased responses. b. Lasts from birth to day 28 of life. c. Applies to full-term births only. d. Varies by socioeconomic status and the mother's age.

ANS: B Changes begin right after birth; the cutoff time when the transition is considered over (although the baby keeps changing) is 28 days. The transition period has three phases: first reactivity, decreased response, and second reactivity. All newborns experience this transition regardless of age or type of birth. Although stress can cause variation in the phases, the mother's age and wealth do not disturb the pattern.

38. The process in which bilirubin is changed from a fat-soluble product to a water-soluble product is known as: a. Enterohepatic circuit. c. Unconjugation of bilirubin. b. Conjugation of bilirubin. d. Albumin binding.

ANS: B Conjugation of bilirubin is the process of changing the bilirubin from a fat-soluble to a water-soluble product. This is the route by which part of the bile produced by the liver enters the intestine, is reabsorbed by the liver, and then is recycled into the intestine. Unconjugated bilirubin is fat soluble. Albumin binding is to attach something to a protein molecule.

4. A newborn is placed under a radiant heat warmer, and the nurse evaluates the infant's body temperature every hour. Maintaining the newborn's body temperature is important for preventing: a. Respiratory depression. b. Cold stress. c. Tachycardia. d. Vasoconstriction.

ANS: B Loss of heat must be controlled to protect the infant from the metabolic and physiologic effects of cold stress, and that is the primary reason for placing a newborn under a radiant heat warmer. Cold stress results in an increased respiratory rate and vasoconstriction.

25. An examiner who discovers unequal movement or uneven gluteal skin folds during the Ortolani maneuver would then: a. Tell the parents that one leg may be longer than the other, but they will equal out by the time the infant is walking. b. Alert the physician that the infant has a dislocated hip. c. Inform the parents and physician that molding has not taken place. d. Suggest that, if the condition does not change, surgery to correct vision problems may be needed.

ANS: B The Ortolani maneuver is a technique for checking hip integrity. Unequal movement suggests that the hip is dislocated. The physician should be notified.

18. By knowing about variations in infants' blood count, nurses can explain to their clients that: a. A somewhat lower than expected red blood cell count could be the result of delay in clamping the umbilical cord. b. The early high white blood cell (WBC) count is normal at birth and should decrease rapidly. c. Platelet counts are higher than in adults for a few months. d. Even a modest vitamin K deficiency means a problem with the ability of the blood to clot properly.

ANS: B The WBC count is high the first day of birth and then declines rapidly. Delayed clamping of the cord results in an increase in hemoglobin and the red blood cell count. The platelet count essentially is the same for newborns and adults. Clotting is sufficient to prevent hemorrhage unless the vitamin K deficiency is significant.

1. A woman gave birth to a healthy 7-pound, 13-ounce infant girl. The nurse suggests that the woman place the infant to her breast within 15 minutes after birth. The nurse knows that breastfeeding is effective during the first 30 minutes after birth because this is the: a. Transition period. b. First period of reactivity c. Organizational stage. d. Second period of reactivity.

ANS: B The first period of reactivity is the first phase of transition and lasts up to 30 minutes after birth. The infant is highly alert during this phase. The transition period is the phase between intrauterine and extrauterine existence. There is no such phase as the organizational stage. The second period of reactivity occurs roughly between 4 and 8 hours after birth, after a period of prolonged sleep.

33. Cardiovascular changes that cause the foramen ovale to close at birth are a direct result of: a. Increased pressure in the right atrium. b. Increased pressure in the left atrium. c. Decreased blood flow to the left ventricle. d. Changes in the hepatic blood flow.

ANS: B With the increase in the blood flow to the left atrium from the lungs, the pressure is increased, and the foramen ovale is functionally closed. The pressure in the right atrium decreases at birth. It is higher during fetal life. Blood flow increases to the left ventricle after birth. The hepatic blood flow changes, but that is not the reason for the closure of the foramen ovale.

37. A meconium stool can be differentiated from a transitional stool in the newborn because the meconium stool is: a. Seen at age 3 days. b. The residue of a milk curd. c. Passed in the first 12 hours of life. d. Lighter in color and looser in consistency.

ANS: C Meconium stool is usually passed in the first 12 hours of life, and 99% of newborns have their first stool within 48 hours. If meconium is not passed by 48 hours, obstruction is suspected. Meconium stool is the first stool of the newborn and is made up of matter remaining in the intestines during intrauterine life. Meconium is dark and sticky.

24. What marks on a baby's skin may indicate an underlying problem that requires notification of a physician? a. Mongolian spots on the back b. Telangiectatic nevi on the nose or nape of the neck c. Petechiae scattered over the infant's body d. Erythema toxicum anywhere on the body

ANS: C Petechiae (bruises) scattered over the infant's body should be reported to the pediatrician because they may indicate underlying problems. Mongolian spots are bluish-black spots that resemble bruises but fade gradually over months and have no clinical significance. Telangiectatic nevi (stork bites, angel kisses) fade by the second year and have no clinical significance. Erythema toxicum is an appalling-looking rash, but it has no clinical significance and requires no treatment.

32. A first-time dad is concerned that his 3-day-old daughter's skin looks "yellow." In the nurse's explanation of physiologic jaundice, what fact should be included? a. Physiologic jaundice occurs during the first 24 hours of life. b. Physiologic jaundice is caused by blood incompatibilities between the mother and infant blood types. c. The bilirubin levels of physiologic jaundice peak between the second and fourth days of life. d. This condition is also known as "breast milk jaundice."

ANS: C Physiologic jaundice becomes visible when the serum bilirubin reaches a level of 5 mg/dL or greater, which occurs when the baby is approximately 3 days old. This finding is within normal limits for the newborn. Pathologic jaundice occurs during the first 24 hours of life. Pathologic jaundice is caused by blood incompatibilities, causing excessive destruction of erythrocytes, and must be investigated. Breast milk jaundice occurs in one third of breastfed infants at 2 weeks and is caused by an insufficient intake of fluids.

6. While examining a newborn, the nurse notes uneven skin folds on the buttocks and a click when performing the Ortolani maneuver. The nurse recognizes these findings as a sign that the newborn probably has: a. Polydactyly. b. Clubfoot. c. Hip dysplasia. d. Webbing

ANS: C The Ortolani maneuver is used to detect the presence of hip dysplasia. Polydactyly is the presence of extra digits. Clubfoot (talipes equinovarus) is a deformity in which the foot turns inward and is fixed in a plantar-flexion position. Webbing, or syndactyly, is a fusing of the fingers or toes

3. While assessing the newborn, the nurse should be aware that the average expected apical pulse range of a full-term, quiet, alert newborn is: a. 80 to 100 beats/min. b. 100 to 120 beats/min. c. 120 to 160 beats/min. d. 150 to 180 beats/min.

ANS: C The average infant heart rate while awake is 120 to 160 beats/min. The newborn's heart rate may be about 85 to 100 beats/min while sleeping. The infant's heart rate typically is a bit higher when alert but quiet. A heart rate of 150 to 180 beats/min is typical when the infant cries.

36. In administering vitamin K to the infant shortly after birth, the nurse understands that vitamin K is: a. Important in the production of red blood cells. b. Necessary in the production of platelets. c. Not initially synthesized because of a sterile bowel at birth. d. Responsible for the breakdown of bilirubin and prevention of jaundice.

ANS: C The bowel is initially sterile in the newborn, and vitamin K cannot be synthesized until food is introduced into the bowel. Vitamin K is necessary to activate blood clotting factors. The platelet count in term newborns is near adult levels. Vitamin K is necessary to activate prothrombin and other clotting factors.

28. During life in utero, oxygenation of the fetus occurs through transplacental gas exchange. When birth occurs, four factors combine to stimulate the respiratory center in the medulla. The initiation of respiration then follows. Which is not one of these essential factors? a. Chemical c. Thermal b. Mechanical d. Psychologic

ANS: D A psychologic factor is not one of the essential factors in the initiation of breathing; the fourth factor is sensory. The sensory factors include handling by the provider, drying by the nurse, lights, smells, and sounds. Chemical factors are essential for the initiation of breathing. During labor, decreased levels of oxygen and increased levels of carbon dioxide seem to have a cumulative effect that is involved in the initiation of breathing. Clamping of the cord may also contribute to the start of respirations. Prostaglandins are known to inhibit breathing, and clamping of the cord results in a drop in the level of prostaglandins. Mechanical factors also are necessary to initiate respirations. As the infant passes through the birth canal, the chest is compressed. With birth the chest is relaxed, which allows for negative intrathoracic pressure that encourages air to flow into the lungs. The profound change in temperature between intrauterine

22. Which statement describing physiologic jaundice is incorrect? a. Neonatal jaundice is common, but kernicterus is rare. b. The appearance of jaundice during the first 24 hours or beyond day 7 indicates a pathologic process. c. Because jaundice may not appear before discharge, parents need instruction on how to assess it and when to call for medical help. d. Breastfed babies have a lower incidence of jaundice.

ANS: D Breastfeeding is associated with an increased incidence of jaundice. Neonatal jaundice occurs in 60% of newborns; the complication called kernicterus is rare. Jaundice in the first 24 hours or that persists past day 7 is cause for medical concern. Parents need to know how to assess for jaundice in their newborn.

10. While evaluating the reflexes of a newborn, the nurse notes that with a loud noise the newborn symmetrically abducts and extends his arms, his fingers fan out and form a "C" with the thumb and forefinger, and he has a slight tremor. The nurse would document this finding as a positive: a. Tonic neck reflex. c. Babinski reflex. b. Glabellar (Myerson) reflex. d. Moro reflex.

ANS: D The characteristics displayed by the infant are associated with a positive Moro reflex. The tonic neck reflex occurs when the infant extends the leg on the side to which the infant's head simultaneously turns. The glabellar reflex is elicited by tapping on the infant's head while the eyes are open. A characteristic response is blinking for the first few taps. The Babinski reflex occurs when the sole of the foot is stroked upward along the lateral aspect of the sole and then across the ball of the foot. A positive response occurs when all the toes hyperextend, with dorsiflexion of the big toe.

30. A nursing student is helping the nursery nurses with morning vital signs. A baby born 10 hours ago by cesarean section is found to have moist lung sounds. What is the best interpretation of these data? a. The nurse should notify the pediatrician stat for this emergency situation. b. The neonate must have aspirated surfactant. c. If this baby was born vaginally, it could indicate a pneumothorax. d. The lungs of a baby delivered by cesarean section may sound moist for 24 hours after birth.

ANS: D The condition will resolve itself within a few hours. For this common condition of newborns, surfactant acts to keep the expanded alveoli partially open between respirations. In vaginal births, absorption of remaining lung fluid is accelerated by the process of labor and delivery. Remaining lung fluid will move into interstitial spaces and be absorbed by the circulatory and lymphatic systems. This is a particularly common condition for infants delivered by cesarean section. Surfactant is produced by the lungs, so aspiration is not a concern.

15. Which statement describing the first phase of the transition period is inaccurate? a. It lasts no longer than 30 minutes. b. It is marked by spontaneous tremors, crying, and head movements. c. It includes the passage of meconium. d. It may involve the infant's suddenly sleeping briefly.

ANS: D The first phase is an active phase in which the baby is alert. Decreased activity and sleep mark the second phase. The first phase is the shortest, lasting less than 30 minutes. Such exploratory behaviors include spontaneous startle reactions. In the first phase the newborn also produces saliva.

8. The nurse assessing a newborn knows that the most critical physiologic change required of the newborn is: a. Closure of fetal shunts in the circulatory system. b. Full function of the immune defense system at birth. c. Maintenance of a stable temperature. d. Initiation and maintenance of respirations.

ANS: D The most critical adjustment of a newborn at birth is the establishment of respirations. The cardiovascular system changes markedly after birth as a result of fetal respiration, which reduces pulmonary vascular resistance to the pulmonary blood flow and initiates a chain of cardiac changes that support the cardiovascular system. The infant relies on passive immunity received from the mother for the first 3 months of life. After the establishment of respirations, heat regulation is critical to newborn survival.

16. With regard to the respiratory development of the newborn, nurses should be aware that: a. The first gasping breath is an exaggerated respiratory reaction within 1 minute of birth. b. Newborns must expel the fluid from the respiratory system within a few minutes of birth. c. Newborns are instinctive mouth breathers. d. Seesaw respirations are no cause for concern in the first hour after birth.

ANS: A The first breath produces a cry. Newborns continue to expel fluid for the first hour of life. Newborns are natural nose breathers; they may not have the mouth-breathing response to nasal blockage for 3 weeks. Seesaw respirations instead of normal abdominal respirations are not normal and should be reported.

27. The nurse caring for the newborn should be aware that the sensory system least mature at the time of birth is: a. Vision. c. Smell. b. Hearing. d. Taste.

ANS: A The visual system continues to develop for the first 6 months. As soon as the amniotic fluid drains from the ear (minutes), the infant's hearing is similar to that of an adult. Newborns have a highly developed sense of smell. The newborn can distinguish and react to various tastes.

23. The cheeselike, whitish substance that fuses with the epidermis and serves as a protective coating is called: a. Vernix caseosa. c. Caput succedaneum. b. Surfactant. d. Acrocyanosis.

ANS: A This protection, vernix caseosa, is needed because the infant's skin is so thin. Surfactant is a protein that lines the alveoli of the infant's lungs. Caput succedaneum is the swelling of the tissue over the presenting part of the fetal head. Acrocyanosis is cyanosis of the hands and feet that results in a blue coloring.

9. The parents of a newborn ask the nurse how much the newborn can see. The parents specifically want to know what type of visual stimuli they should provide for their newborn. The nurse responds to the parents by telling them: a. "Infants can see very little until about 3 months of age." b. "Infants can track their parent's eyes and distinguish patterns; they prefer complex patterns." c. "The infant's eyes must be protected. Infants enjoy looking at brightly colored stripes." d. "It's important to shield the newborn's eyes. Overhead lights help them see better."

ANS: B "Infants can track their parent's eyes and distinguish patterns; they prefer complex patterns" is an accurate statement. Development of the visual system continues for the first 6 months of life. Visual acuity is difficult to determine, but the clearest visual distance for the newborn appears to be 19 cm. Infants prefer to look at complex patterns, regardless of the color. Infants prefer low illumination and withdraw from bright light.

41. Plantar creases should be evaluated within a few hours of birth because: a. The newborn has to be footprinted. b. As the skin dries, the creases will become more prominent. c. Heel sticks may be required. d. Creases will be less prominent after 24 hours.

ANS: B As the infant's skin begins to dry, the creases will appear more prominent, and the infant's gestation could be misinterpreted. Footprinting will not interfere with the creases. Heel sticks will not interfere with the creases. The creases will appear more prominent after 24 hours.

42. What are modes of heat loss in the newborn (Select all that apply)? a. Perspiration b. Convection c. Radiation d. Conduction e. Urination

ANS: B, C, D Convection, radiation, evaporation, and conduction are the four modes of heat loss in the newborn. Perspiration and urination are not modes of heat loss in newborns.

21. With regard to the gastrointestinal (GI) system of the newborn, nurses should be aware that: a. The newborn's cheeks are full because of normal fluid retention. b. The nipple of the bottle or breast must be placed well inside the baby's mouth because teeth have been developing in utero, and one or more may even be through. c. Regurgitation during the first day or two can be reduced by burping the infant and slightly elevating the baby's head. d. Bacteria are already present in the infant's GI tract at birth because they traveled through the placenta.

ANS: C Avoiding overfeeding can also reduce regurgitation. The newborn's cheeks are full because of well-developed sucking pads. Teeth do develop in utero, but the nipple is placed deep because the baby cannot move food from the lips to the pharynx. Bacteria are not present at birth, but they soon enter through various orifices.

11. While assessing the integument of a 24-hour-old newborn, the nurse notes a pink, papular rash with vesicles superimposed on the thorax, back, and abdomen. The nurse should: a. Notify the physician immediately. b. Move the newborn to an isolation nursery. c. Document the finding as erythema toxicum. d. Take the newborn's temperature and obtain a culture of one of the vesicles.

ANS: C Erythema toxicum (or erythema neonatorum) is a newborn rash that resembles flea bites. This is a normal finding that does not require notification of the physician, isolation of the newborn, or any additional interventions.

17. With regard to the newborn's developing cardiovascular system, nurses should be aware that: a. The heart rate of a crying infant may rise to 120 beats/min. b. Heart murmurs heard after the first few hours are cause for concern. c. The point of maximal impulse (PMI) often is visible on the chest wall. d. Persistent bradycardia may indicate respiratory distress syndrome (RDS).

ANS: C The newborn's thin chest wall often allows the PMI to be seen. The normal heart rate for infants who are not sleeping is 120 to 160 beats/min. However, a crying infant temporarily could have a heart rate of 180 beats/min. Heart murmurs during the first few days of life have no pathologic significance; an irregular heart rate past the first few hours should be evaluated further. Persistent tachycardia may indicate RDS; bradycardia may be a sign of congenital heart blockage.

5. An African-American woman noticed some bruises on her newborn girl's buttocks. She asks the nurse who spanked her daughter. The nurse explains that these marks are called: a. Lanugo. b. Vascular nevi. c. Nevus flammeus. d. Mongolian spots.

ANS: D A Mongolian spot is a bluish black area of pigmentation that may appear over any part of the exterior surface of the body. It is more commonly noted on the back and buttocks and most frequently is seen on infants whose ethnic origins are Mediterranean, Latin American, Asian, or African. Lanugo is the fine, downy hair seen on a term newborn. A vascular nevus, commonly called a strawberry mark, is a type of capillary hemangioma. A nevus flammeus, commonly called a port-wine stain, is most frequently found on the face.

19. What infant response to cool environmental conditions is either not effective or not available to them? a. Constriction of peripheral blood vessels b. Metabolism of brown fat c. Increased respiratory rates d. Unflexing from the normal position

ANS: D The newborn's flexed position guards against heat loss because it reduces the amount of body surface exposed to the environment. The newborn's body is able to constrict the peripheral blood vessels to reduce heat loss. Burning brown fat generates heat. The respiratory rate may rise to stimulate muscular activity, which generates heat.

26. One reason the brain is vulnerable to nutritional deficiencies and trauma in early infancy is the: a. Incompletely developed neuromuscular system. b. Primitive reflex system. c. Presence of various sleep-wake states. d. Cerebellum growth spurt.

ANS: D The vulnerability of the brain likely is to the result of the cerebellum growth spurt. The neuromuscular system is almost completely developed at birth. The reflex system is not relevant. The various sleep-wake states are not relevant.