Data from 354 embryos anti fetuses between 20 and 200 mm orown-rump length obtained by therapeutic abortion in 3 different countries have been evaluated. Comparison with Strektkr's widely used averages indicated significant differences at the early developmental stages. Towards and in the second trimester of gestation the discrepancies between the old and the here presented new standards of fetal growth have diminished considerably. The possible reasons for the marked deviations at the early developmental levels - and for the lack of the same in more advanced stages - have been discussed.
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