When measuring a newborn's chest circumference, where should the nurse position the tape measure?

Positioning the tape measure at the level of the nipples when measuring a newborn's chest circumference is the standard practice. This location provides the most accurate measurement as it encompasses the widest part of the chest, which typically aligns with the level of the nipples. This ensures that the measurement accurately reflects the baby's thoracic development and growth.

Measuring at the level of the umbilicus, 2 inches below the nipples, or in the axillary area would not provide an accurate representation of the chest circumference. The umbilicus is associated with the abdominal area, which is not relevant for chest circumference. Similarly, measuring below the nipples or in the axillary area would not capture the chest's full circumference, potentially leading to misleading data concerning the newborn's growth and health.