The ratio of upper body segment to lower body segment changes from 1.7 at birth to 1.0 by what age?
- 2 years
- 4 years
- 7 years
- 10 years
- Puberty
Body proportions follow a predictable sequence of changes with development. The head and trunk are relatively large at birth, with progressive lengthening of the limbs throughout development, particularly during puberty. The lower body segment is defined as the length from the symphysis pubis to the floor, and the upper body segment is the height minus the lower body segment. The ratio of upper body segment divided by lower body segment (U/L ratio) equals approximately 1.7 at birth, 1.3 at 3 yr of age, and 1.0 after 7 yr of age. Higher U/L ratios are characteristic of short-limb dwarfism or bone disorders, such as rickets.
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