Solution:
Fetal programming occurs during embryonic and fetal development, a critical period in which tissues and organs are created. Insufficient nutrition during this time results in permanent alterations to certain structural and physiological metabolic functions of the fetus. British epidemiologist Barker first established the hypothesis, known as the "Barker hypothesis,” which states such programmed changes during this critical period predispose the fetus to certain postnatal diseases. The critical period coincides with the timing of rapid cell differentiation. Essentially, it refers to the process of sustaining or affecting a stimulus or impairment that occurs at a crucial point in its development.
Rickets has long demonstrated that under nutrition in the critical early stages of life brings about a continuing change in structure. A recent new doctrine suggests that fetal programming can affect diseases in adulthood. That is, the body's “memory” of under nutrition during the early stages of development translates into a pathology that determines future diseases. This idea is based on animal studies that demonstrate how under nutrition in utero can alter blood pressure, cholesterol metabolism, insulin response to glucose, and other metabolic, endocrine, and immune functions important to human diseases. This paper reviews evidence of the correlation between fetal under nutrition and diseases found in previous studies and considers the mechanism of fetal programming and the role of the placenta.