Epidemic Occurrence, or outbreak, of a given disease, or group of similar illnesses in a popula- tion, or region vastly exceeding usual prevalence, affecting large proportions of the population. Epidemiology Study of the distribution of factors which determine health and disease in populations. Immunisation Artificial production of immunity, by use of a vaccine or passive introduction of an immunoglobulin. Intrauterine growth restriction (IUGR) Where a fetus has failed to achieve its growth potential, resulting in the birth of a baby whose birth weight is abnormally low in relation to gestational age. Macrosomia Abnormally large for gestational age. Morbidity The state of being ill or having a disease. Mortality Death. Obesity Condition in which excess fat has accumulated in the body, mostly in the subcutaneous tissues.