The Placenta: The Lost Neuroendocrine Organ

Abstract

The placenta long has been underappreciated and understudied by the scientific community. Improper function of this critical organ causes fetal abnormalities, preterm labor, and the most common disease of pregnancy, preeclampsia. Despite the importance of the placenta, understanding of its role in fetal development, especially at a molecular level, is crude. Sadly, understanding of placental function may be compared with the knowledge of kidney function 50 years ago in that researchers can describe the anatomy but not the biology. As an endocrine organ, the placenta produces a wide array of hormones that affect both mother and fetus as well as the development of the placenta itself. Most research on placental endocrinology has focused either on parameters of fetal growth or placentally induced changes in maternal physiology that support pregnancy. The possibility that placental hormones may have direct effects on the developing fetus deserves increased attention. Placental endocrine function can be disrupted by abnormal gene expression, infection, or prematurity, resulting in long-term damage from loss of the normal hormonal milieu. In this review, we focus on placental endocrine function related to fetal well-being, particularly neurodevelopment. Better understanding of this function may open new avenues to therapeutic treatments to improve developmental outcome in fetuses and infants at high risk of developmental brain damage.