Magnesium levels in the body fluids of dam and fetal rabbits during the reproductive phase.

Gestation- and lactation-dependent variations of magnesium concentrations were measured in the maternal and fetal body fluids and tissues of rabbits. Samples of serum, milk, and mammary gland were investigated. A decrease in magnesium in the maternal serum during the early gestation period from 0.80 mmol/l in the first week to 0.73 mmol/l in the third week was observed. In the last week of gestation a rapid increase of magnesium concentrations both in maternal (0.83 mmol/l) and fetal (2.84 mmol/l) serum was determined. An assumed active diaplacental transfer of magnesium from the doe to the fetus was indirectly established. An active transport mechanism for magnesium from the maternal serum into the mammary glands was enhanced by strong concentration gradients of approximately 1:33 between serum and milk.