In 1989, David Barker, M.D., Ph.D., F.R.S., reported the relationship between birth weight and death rates from coronary heart disease in both men and women in Hertfordshire, UK. He showed that among adults who had been born in the birth weight range of 5 to 9 pounds, more men and women died of heart disease when they were born on the lighter end of that range than on the heavier end. He also showed that being born above 9.5 pounds carried a particularly high risk for heart disease. These data initiated a new field of medicine, known as the Developmental Origins of Health and Disease (DOHAD). Research in this field has since demonstrated that stresses experienced in the womb – virtually all of which have roots in the social and physical environment — alter the structures of organs in the fetus, thus changing the expression of regulatory genes throughout the lifetime. Together, these two processes lead to vulnerability for disease in later life.