PLACENTAL CONTROL OF FETAL GROWTH

The placenta exerts its effects on the growth of the fetus from the be ginning of pregnancy via metabolic and endocrine mechanisms. To achiev e this, the placenta exchanges a wide array of nutrients, endocrine si gnals, cytokines and growth factors with the mother and the fetus. The se exchanges modulate or programme fetal growth and development. This review concentrates on the function and structure of the placenta in h umans and in animals, and the effects of experimental perturbation of placental size and function on fetal growth. The consequences for feta l growth of varying the abundance of peptides or, by deleting genes, i nsulin-like growth factors or cytokines, are also described. Maternal nutritional and hormonal state from as early as the first few days aft er fertilization, can influence the growth rate of the placenta and th e fetus and also the length of gestation. Influences on placental deve lopment and their consequences will clearly have an impact on the plac ental control of fetal growth. Variations in the maternal environment and consequent perturbation of the metabolic and endocrine environment of the placenta and fetus are implicated as being responsible for the associations between prenatal growth of the placenta and its fetus an d the subsequent risk of adult disease. The next challenge will be to determine the dominant influences at each stage of fetal and placental growth.