Magnesium and intrauterine growth restriction

Background: The presence of intrauterine growth restriction (IUGR), could potentially lead to imbalances of Mg homeostasis, which have not yet been fully clarified. Objective: To describe, in term. newborn (NB) without IUGR, ionized magnesium (iMg) and total magnesium (TMg) concentrations in umbilical cord blood, on the third and seventh days of life and to compare these values with those of term NB with IUGR. Methods: A prospective study was performed on 70 term NB divided into two groups: Group I-30 NB without IUGR and Group II-40 NB with IUGR. TMg concentrations were determined in sera by a classical colorimetric end point method (Cobas-Mira, Roche), and iMg was determined in whole blood by means of the Stat Profile-M analyzer (NOVA Biomedical). Results: We found that in term NB without IUGR, TMg concentrations increased during the first week of life and were lower than those of NB with IUGR in cord blood (p < 0.05). NB without IUGR had decreased iMg concentrations in comparison to NB with IUGR in all sampling times, i.e., cord blood, third and seventh days of life (p < 0.001). iMg concentrations remained unchanged during the study period. We also found that all NB enrolled in the study presented with low iMg concentrations (reference interval 0.4-0.6 mmol/L). Conclusion: The presence of IUGR may influence neonatal levels of magnesium, suggesting an effect on the modulation of this ion homeostasis, during the perinatal period.