2 - Fetal Development, Physiology, and Effects on Long-Term Health

Abstract

Placental and fetal physiology provide the foundation for understanding pathophysiology and thus mechanisms of disease. Much of our knowledge of fetal physiology derives from observations in mammals other than humans, although we included only observations applicable to the human fetus in the first half of this chapter. The early development and physiology program and predict offspring phenotype. The newborn and adult body contain approximately 2.1 × 1012 and 3.7 × 1013 human cells, respectively. Beginning with a fertilized ovum, it would require more than 41 cell division cycles to form a newborn and a total of 45 cycles for an adult. Thus more than 90% of lifetime cell divisions for body growth occur by the time of birth. Therefore it should not be surprising that the maternal/fetal environment may alter cell signaling, epigenetic regulation, and organ development, with nutrient environment alterations specifically impacting energy-regulating organs. This topic is covered in the second half of the chapter.