Magnesium deficiency during pregnancy in mice impairs placental size and function.

Objective: Maternal magnesium (Mg) deficiency has been associated with fetal growth restriction. Using a mouse model of maternal Mg deficiency-induced fetal growth restriction, we sought to investigate the effect of Mg deficiency on placental physiology and function.

Methods: In vivo: Pregnant Swiss Webster mice were fed either 100% of the recommended amount of Mg (control) or 10%Mg (Mg-deficient) (8 per group). Dams were euthanized on gestational day 17 and placentas were collected, weighed and assessed for Mg concentrations, as well as nutrient transporter mRNA expression. For nutrient transfer studies, control and Mg-deficient dams (6 per group) were injected with (14)C-amino acids and (3)H-glucose and trans-placental passage was determined. In vitro: BeWo placental cells were grown in media containing 10%Mg to 100%Mg and the effects of Mg status on cell proliferation, oxidative stress and nutrient uptake were measured. Data were analyzed by Student's t-tests comparing controls vs. Mg-deficient animals or cells. For multiple comparisons, data were analyzed by ANOVA followed by Dunnett's post hoc testing.

Results: In vivo: Maternal Mg deficiency decreased placental Mg content, placental and fetal weights, ratio of fetal:placental weight (P < 0.05), placental Slc7a5 transporter mRNA expression and transplacental nutrient transport (P < 0.05). In vitro: Mg deficiency reduced BeWo nutrient uptake (P < 0.01) and cell proliferation (P < 0.01), and increased oxidative stress (P < 0.01).

Conclusion: These findings highlight the adverse effects of maternal Mg deficiency on fetal weight and placental function, including transport and proliferation and may explain the fetal growth restriction observed with moderate Mg deficiency in mice.