A first-time father is changing the diaper of his 1-day-old daughter. He asks the nurse, "What is this black, sticky stuff in her diaper?" The nurse's best response is:

Choice a) 100 to 120 is incorrect because this is too low for a normal newborn's heart rate. The heart rate of a newborn is influenced by factors such as gestational age, activity level, temperature, and health status. A full-term, quiet, alert newborn should have a heart rate between 120 and 160 beats per minute, which reflects their high metabolic rate and oxygen demand. A heart rate below 100 beats per minute may indicate bradycardia, which can be caused by hypoxia, hypothermia, or cardiac problems.

Choice b) 120 to 160 is correct because this is the normal range for a full-term, quiet, alert newborn's heart rate. The apical pulse is the best way to measure the heart rate of a newborn, as it reflects the actual contractions of the heart. The apical pulse can be auscultated at the fourth intercostal space on the left side of the chest, just below the nipple line. The nurse should count the apical pulse for a full minute, as it may vary with the respiratory cycle.

Choice c) 80 to 100 is incorrect because this is also too low for a normal newborn's heart rate. A full-term, quiet, alert newborn should have a heart rate between 120 and 160 beats per minute, which is higher than that of an adult or an older child. A heart rate below 100 beats per minute may indicate bradycardia, which can be caused by hypoxia, hypothermia, or cardiac problems.

Choice d) 150 to 180 is incorrect because this is too high for a normal newborn's heart rate. A full-term, quiet, alert newborn should have a heart rate between 120 and 160 beats per minute, which is lower than that of a preterm or a crying newborn. A heart rate above 160 beats per minute may indicate tachycardia, which can be caused by fever, infection, anemia, or hyperthyroidism.

Choice A: This is incorrect because both physiological and nonphysiological jaundice result from breakdown of erythrocytes. Jaundice is caused by the accumulation of bilirubin, a yellow pigment that is produced when red blood cells are destroyed. However, the rate and extent of hemolysis differ between the two types of jaundice.

Choice B: This is incorrect because kernicterus is a rare and serious complication of jaundice, not a usual outcome. Kernicterus occurs when bilirubin levels are very high and the pigment deposits in the brain, causing neurological damage. It can affect both physiological and nonphysiological jaundice, but it is more likely to occur in nonphysiological jaundice due to higher bilirubin levels and underlying conditions.

Choice C: This is incorrect because both physiological and nonphysiological jaundice begin at the head and progress down the body. This is because bilirubin accumulates in areas with high fat content, such as the skin, eyes, and brain. The distribution of jaundice depends on the level of bilirubin in the blood, not on the type of jaundice.

Choice D: This is the correct answer because nonphysiological jaundice appears in the first 24 hours of life, whereas physiological jaundice appears after the first 24 hours of life. Nonphysiological jaundice is caused by factors that increase hemolysis or impair bilirubin metabolism or excretion, such as blood group incompatibility, infection, liver disease, or enzyme deficiency. Physiological jaundice is caused by normal adaptation processes that occur after birth, such as increased red blood cell turnover, immature liver function, and delayed intestinal flora colonization.