Which statement accurately describes a cardiovascular change that occurs in the first year of life?

Which statement accurately describes a cardiovascular change that occurs in the first year of life?

• A. The heart doubles in size and the pulse rate decreases from 120-140 to about 100.
• B. The heart shrinks slightly and the pulse rate increases to 160.
• C. The heart doubles in size but pulse rate remains 120-140.
• D. The heart size remains constant and pulse rate decreases to 90.

Answer: (A)

In the first year of life, the cardiovascular system undergoes rapid growth in parallel with the child’s overall development. The heart enlarges substantially as the chest cavity and body mass increase, with the heart roughly doubling in size during this period. At the same time, the resting pulse rate slows as autonomic control matures and metabolic demands become steadier, dropping from about 120–140 beats per minute in infancy toward about 100 beats per minute by the end of the first year. This combination of increasing heart size and decreasing heart rate fits the expected pattern of infancy cardiovascular maturation. The other described patterns—the heart shrinking, the pulse rate increasing to very high levels, or the pulse rate staying the same—do not align with how the infant’s heart size and rate typically change during the first year.

In the first year of life, the cardiovascular system undergoes rapid growth in parallel with the child’s overall development. The heart enlarges substantially as the chest cavity and body mass increase, with the heart roughly doubling in size during this period. At the same time, the resting pulse rate slows as autonomic control matures and metabolic demands become steadier, dropping from about 120–140 beats per minute in infancy toward about 100 beats per minute by the end of the first year. This combination of increasing heart size and decreasing heart rate fits the expected pattern of infancy cardiovascular maturation.

The other described patterns—the heart shrinking, the pulse rate increasing to very high levels, or the pulse rate staying the same—do not align with how the infant’s heart size and rate typically change during the first year.