The relationship between differences in regional growth rates and changes in shape during human fetal craniofacial growth.

Large differences in growth rates between various craniofacial regions have been reported but have not distinguished between absolute and relative rates. Measurements on 60 fetuses, 49-212 mm crown-rump length, showed that absolute growth rates correlated highly with size of the craniofacial region measured (r = 0.9996, p less than 0.001) but were unrelated to changes in shape and relative proportion. By standardizing for size, absolute growth rates were converted into relative growth rates which correlated with changes in relative proportion and thus shape (r = 0.785, p less than 0.001).