Body Proportions

Body proportions change considerably during fetal and postnatal life. For example, during fetal life the head appears disproportionately large compared with the body. Beginning about eight months in utero subcutaneous fat begins to accumulate, and from then until birth the major changes in proportions are due to the accumulation of fat (Fig. 3.1).

The alteration of body configuration is the result of selective regional growth. In infancy the head grows most rapidly, so that during the first year of life, OFC is greater than chest circumference. After the first year, head growth slows down. At birth the limbs are shorter than the trunk; they grow more rapidly and proportions are reversed. Leg growth ceases somewhat earlier than growth of the arms.

The changing proportions are mainly reflected in two ratios. First, the upper/lower segment ratio is the ratio of the distance from the top of

Figure 3.1 Body proportions during human development.

Figure 3.1 Body proportions during human development.

Intrauterine

Chapter 3 Proportional Growth and Normal Variants the head to the symphysis pubis and the distance from the symphysis pubis to the sole of the foot. At birth, this ratio is about 1.7; at 10 years of age, it is about 1.0; after 10 years of age, the ratio is normally less than 1.0. The second ratio is the comparison of span with height. At birth, the span is over an inch less than height. Normally in boys, the span exceeds standing height by about 10 years of age; in girls normally, span exceeds height at about 12 years of age.

Pregnancy And Childbirth

Pregnancy And Childbirth

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