during pregnancy are both linked to high blood pressure in the offspring during adulthood. Mouse models suggest that this is due to high levels of the fetal hormone leptin, which is present in the blood of individuals that are overweight or obese. There is a theory that this hormone has a negative impact on the regulatory systems of the fetus, and renders it impossible to maintain normal blood pressure levels. Insufficient nutrition Pre-eclampsia, involving oxygen deprivation and death of trophoblastic cells that make up most of the placenta, is a disease which is often associated with maladaptive long-term consequences of inappropriate fetal programming. Here, an inadequately developed and poorly functioning placenta fails to meet the fetus’ nutritional needs during gestation, either by altering its selection for nutrients which can cross into fetal blood or restricting total volume thereof. Consequences of this for the fetus in adult life include cardiovascular and metabolic conditions. Hormonal influence A delicate balance of hormones during pregnancy is regarded as being highly relevant to fetal programming and may significantly influence the outcome on the offspring. Placental endocrine transfer from the mother to the developing fetus could be altered by the mental state of the mother, due to affected glucocorticoid transfer that takes place across the placenta. Thyroid Thyroid hormones play an instrumental role during the early development of the fetus's brain. Therefore, mothers suffering from thyroid-related issues and altered thyroid hormone levels may inadvertently trigger structural and functional changes in the fetal brain. The fetus is able to produce its own thyroid hormones from the onset of the second trimester; however, maternal thyroid hormones are important for brain development before and after the baby is able to synthesize the hormones while still in the uterus. Due to this, the baby may experience an increased risk of neurological or psychiatric diseases later in life. Cortisol Cortisol (and glucocorticoids more generally) is the most well studied hormonal mechanism that may have prenatal programming effects. Although cortisol has normative developmental effects during prenatal development, excess cortisol exposure has deleterious effects on fetal growth, the postnatal function of physiological systems such as the hypothalamic-pituitary-adrenal axis and brain structure or connectivity (eg., amygdala). During gestation, cortisol concentrations in maternal circulation are up to ten times higher than cortisol concentrations in fetal circulation. The maternal-to-fetal cortisol gradient is maintained by the placenta, which forms a structural and enzymatic barrier to cortisol. During