Magnesium is essential for development and the maintenance of normal cellular processes within the body. Experimental and epidemiological evidence suggests that magnesium deficiency can exacerbate cardiovascular and renal disease. During pregnancy, alterations in the foetal environment can influence the health of the offspring; in particular, a suboptimal environment during pregnancy can ‘program’ for cardiovascular disease in adulthood. Whilst magnesium is recognised as being important in foetal development, how altered magnesium levels during pregnancy may affect the health of the offspring remains unknown. This project investigates the role of magnesium in foetal development and developmental programming, and the involvement of magnesium channels in this process. In particular, we have examined how altered magnesium levels affect the health of the offspring in normal pregnancies, and the molecular and cellular mechanisms underlying these events. We have used a magnesium-deficient diet (0.005% Mg) to induce hypomagnesaemia in female CD1 mice prior to mating and pregnancy. Our results show that following four weeks on a magnesium-deficient diet, urinary magnesium was reduced by more than 85% (from 40 mmol/L to 5 mmol/L) when compared to the normal control diet (0.2% Mg). Maternal hypomagnesaemia increased the incidence of embryo resorption during mid-gestation to 70%, as compared to 1% resorption in the control diet. No observational differences in body or organ weights were seen between foetuses of the normal control and the surviving magnesium-deficient groups in late-gestation (E18.5). However, postnatal growth restriction was evident in magnesium-deficient offspring (PN5). Currently, we are investigating the effect of a moderate magnesium-deficient diet (0.02% Mg) to further discern the role of magnesium during embryogenesis. By elucidating physiological mechanisms that underlie magnesium transport, homeostasis, and how this may affect foetal development, we may develop a greater understanding of the importance of magnesium and its role in the development of disease.