How much of an infant's total body weight is estimated to be water?

Infants typically have a higher percentage of body water compared to adults, with estimates generally indicating that about 75% of their total body weight is made up of water. This higher water content is crucial for various physiological processes, including nutrient transport and temperature regulation. As children grow and develop, their body water percentage decreases, stabilizing to around 60-70% in childhood and eventually settling to lower percentages in adulthood.

The other choices suggest percentages that are lower than the established estimate for infants. While body water composition does vary based on numerous factors, the widely accepted understanding highlights that infants' bodies are substantially hydrated compared to both older children and adults, which reinforces the understanding that 75% is the most accurate figure for an infant's total body weight made up of water.