TEN PRINCIPLES OF PROGRAMMING – See Chapters 17 and 18.

Developmental Programming can be defined as: responses made by the fetus to challenges at different stages of development that alter the body’s structure and function and can have long-term effects on health by changing the later-life phenotype.

 

Research into developmental programming hardly existed when the first edition of Life Before Birth was published. As this book shows, developmental programming is now seen as a major influence on our life-course health. Currently, multiple international societies are involved in programming research around the world.

1.   During development, there are critical periods of vulnerability to sub-optimal conditions. Vulnerable periods occur at different times for different tissues. Cells dividing rapidly are at greatest risk. Factors that increase risk include:

·  Too much of a biological molecule normally found in the body such as a hormone, critical nutrient, or vitamin;

·  Deficiency of a biological molecule normally found in the body such as a hormone, critical nutrient, or vitamin;

·  Abnormal molecules not normally found in the body such as drugs of abuse, alcohol or nicotine;

·  Abnormal physical forces, such as high blood pressure.

2.   Programming can have persistent, even permanent, effects that alter responses to challenges in later life and modify susceptibility to disease. These persistent programmed outcomes may have further programming consequences producing a cascade of unwanted outcomes.

3.   Fetal development is activity-dependent. Normal development is dependent on continuing normal activity. Each phase of development provides the required conditions for subsequent development.

4.   Programming involves several different structural changes in important organs:

·  The absolute numbers of cells in the organ may increase or decrease;

·  The relative numbers and distribution of different types of cell within the organ may be unbalanced;

·  The blood supply to the organ may not form adequately;

·  Too many or too few hormone receptors may form with a resultant abnormal setting of feedback and other control mechanisms;

·  Disordered mitochondrial function.

5.   The placenta plays a key role in programming.

6.   Compensation by the fetus that occurs in response to challenges can carry a price. In an unfavorable environment, the developing fetus makes attempts to compensate for deficiencies. Following compensation, birthweight may be normal or only slightly decreased. However, the cell changes made in the compensatory effort can carry a price by making the baby more susceptible to later life obesity.

7.   Attempts made after birth to reverse the consequences of programming may have their own unwanted consequences. When postnatal conditions prove to be other than those to which the fetus adapted, problems may arise from what is called a “mismatch in adaptation”.

8.   Fetal cellular mechanisms often differ from adult processes. Fetuses often react differently to suboptimal conditions than do newborn babies or adults.

9.   The effects of programming may pass across generations by epigenetic mechanisms that do not involve changes in gene structure.

10.   Programming is sex-dependent and often has different outcomes in males and females.