Pregnancy is a physiologically demanding process, vulnerable to several modifiable lifestyle factors including diet. Malnutrition, or a dietary imbalance, can have severe implications on maternal physiology, as well as placental and fetal development. Several aberrant pregnancy outcomes have been linked with an abnormal diet disturbing maternal metabolism, hormone status and placental function. Dietary changes also disrupt the intrauterine environment for the developing fetus, altering growth and predisposing offspring to development of diseases later in life. Abnormal pregnancy outcomes are dependent on the specific timing and type of dietary insult. A major micronutrient deficiency present in multiple human populations is selenium. Deficiencies in micronutrients, such as selenium, have been linked to numerous pregnancy complications; however, the specific ramifications of a selenium deficient diet on pregnancy outcomes and fetal development is relatively unknown. Selenium is incorporated into selenoproteins involved in numerous biological and cellular processes including antioxidant function, thyroid hormone metabolism, endoplasmic reticulum stress and skeletal muscle development. Given selenium is associated with undesirable pregnancy outcomes, the primary aim of this thesis was to investigate the effects of selenium deficiency on pregnancy physiology, placental function, fetal development and offspring outcomes. [...]