What is this barker hypothesis about sick babies making sick adults later in life?

Epigenetics. Barker theory is low birth weight babies make changes to their metabolism/organs that benefit them short term, but hurt them long term. Low birth weight babies are at higher risk for coronary heart disease, hypertension, stroke and diabetes. Low birth weight can be caused by poor maternal health and nutrition. Thus the environment/economics of the mother can affect baby/future adult.