Review: Placenta, evolution and lifelong health.

The intrauterine environment has an important influence on lifelong health, and babies who grew poorly in the womb are more likely to develop chronic diseases in later life. Placental function is a major determinant of fetal growth and is therefore also a key influence on lifelong health. The capacity of the placenta to transport nutrients to the fetus and regulate fetal growth is determined by both maternal and fetal signals. The way in which the placenta responds to these signals will have been subject to evolutionary selective pressures. The responses selected are those which increase Darwinian fitness, i.e. reproductive success. This review asks whether in addition to responding to short-term signals, such as a rise in maternal nutrient levels, the placenta also responds to longer-term signals representing the mother's phenotype as a measure of environmental influences across her life course. Understanding how the placenta responds to maternal signals is therefore not only important for promoting optimal fetal growth but can also give insights into how human evolution affected developmental history with long-term effects on health and disease.