Which of the following statements regarding toddlers and preschoolers is correct?

• A. The normal respiratory rate in toddlers and preschoolers is between 12-20 breaths/min
• B. Toddlers and preschoolers have well-developed lung musculature, even though they have less lung tissue
• C. muscle mass and bone density decrease in toddlers and preschoolers because of increased physical activity
• D. toddlers and preschoolers commonly experience upper respiratory infections because of the loss of passive immunity

Answer: (D)

The statement that toddlers and preschoolers commonly experience upper respiratory infections because of the loss of passive immunity is accurate and reflects a foundational understanding of the developmental immunology of young children. Passive immunity is the immunity that an infant receives from the mother, chiefly through the placenta during pregnancy and through breast milk after birth. As children grow, particularly upon entering toddlerhood and preschool years, they begin to lose this passive immunity and become more susceptible to infections, including upper respiratory infections. This transition is important as it marks the period when children start developing their own immune systems, which may not yet be fully equipped to handle infectious agents effectively, leading to a higher incidence of illness.

Additionally, this susceptibility is compounded by other factors, such as increased social interactions and exposure to various pathogens when children start attending daycare or preschool, further increasing their chances of experiencing infections. Overall, the statement captures a significant aspect of the health dynamics found in toddlers and preschoolers.