A study published in the American Journal of Epidemiology (1990; 132(6):1111–1119) examined birth and early-life records of 257 patients with inflammatory bowel disease (IBD) born between 1924 and 1957 and compared them with 514 healthy controls matched for date of birth, sex, and maternal age. The researchers found that infections occurring before or shortly after delivery were associated with a fourfold increased risk of developing IBD later in life, with viral infections accompanied by fever representing a particularly strong risk factor. Lower socioeconomic status during childhood was also associated with increased risk. Breastfeeding was not found to influence IBD incidence in this cohort. The study also suggested a role for genetic susceptibility. In addition, exposure to cigarette smoke appeared relevant: children exposed to adult smoking, or whose mothers smoked during pregnancy, showed an increased risk for developing Crohn’s disease, though not ulcerative colitis. Supporting this observation, research published in Gastroenterology (April 1992; 102(4)) compared 39 patients with ulcerative colitis and 33 patients with Crohn’s disease to healthy controls and reported a dose-dependent relationship between cigarette smoke exposure and the development of inflammatory bowel disease.