Regional variations in the levels of zinc, iron, copper, and calcium in the term human placenta.

This study investigated the influence of the location of the sampling site during elemental analyses of 21 human term placentae. The levels of iron, zinc, copper and calcium in fetal membranes, umbilical cords and placental discs were measured by atomic absorption spectrophotometry and compared. The disc samples were obtained from central (peri-insertion and mid-disc fetal and maternal halves), and peripheral regions. Significant variations were found. Copper was present in highest levels (17.2 +/- 2.0 micrograms/g dry weight) in the fetal membranes. Calcium levels were highest (712 +/- 47 micrograms/g dry weight) in the periphery of the placental disc. Iron levels were highest (558 +/- 14 micrograms/g dry weight) in the central regions of the disc. Zinc levels were lower (50.3 +/- 1.4 micrograms/g dry weight) in the fetal half of the mid-disc regions than in the maternal half (56.0 +/- 1.2 micrograms/g dry weight). This study demonstrates the importance of defining the location of the sampling site in studies involving elemental analysis of the placenta.