Fetal skin permeability to isotopic water (THO) in early pregnancy

Permeability of fetal skin to isotopic water (THO) was measured between 12 and 24 week's gestational age. Unkeratinized skin obtained from human fetuses between 12 and 18 cm. crown-rump length gave large permeability values similar to amnion and chorion laeve. Partially and well keratinized skin from 18 to 22.5 cm. crown-rump length fetuses showed little and no permeability, respectively, to THO diffusion. These data suggest that fetal skin may function as a site of significant water and solute exchange between fetus and amniotic fluid during early pregnancy.