Biotin plasma levels of the human fetus.

Biotin is an important vitamin for cellular function and growth and, therefore, essential for fetal development. The fetus is exclusively dependent on maternal biotin supply. Since biotin is not produced within the body, maternal biotin levels depend on dietary intake. In order to investigate the biotin status of the human fetus, we measured the plasma biotin levels in 15 pregnant women and their fetuses who underwent amniocentesis and fetal blood sampling at 18-24 weeks of gestation for prenatal diagnosis of thalassemia. Maternal biotin was found to be 131 +/- (SD) 102 ng/l and fetal biotin 784 +/- 327 ng/l (p < 0.0001). Our findings are indicative of an active transport mechanism of biotin through the placenta in favor of the fetus.