A
B |
Embryonic period
Fetal period |
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Fig. 18
Segment A represents the embryonic period in which the embryo is especially sensitive with respect to developmental abnormalities. Within the first eight weeks, the incidence of deformities (blue curve), which lead to miscarrieages, decreases from more than 10% to 1%. The frequency of neural tube defects decreases from 2.5% to 0.1% (green curve) by the end of the embryonic period (3).
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