Fetal and perinatal risk factors for inflammatory bowel disease

Aim: To study the influence of specific factors and events during pregnancy and the perinatal period on the risk of children developing inflammatory bowel disease. Methods: Population-based national register study. Linkage between the Swedish Medical Birth Register and the Swedish Hospital Discharge Register during the period 1987 to 2000 identified 455 singleton infants who later developed inflammatory bowel disease. Data for these children were compared with data for all children born in Sweden during the same period. Results: Smoking during early pregnancy reduced the risk of inflammatory bowel disease ( odds ratio ( OR) 0.71, 95% CI 0.55-0.91). For ulcerative colitis the odds ratio was 0.70 ( 95% CI 0.56-0.86), and for Crohn's disease 0.73 ( 95% CI 0.58 - 0.94). Infections during the neonatal period seemed to increase the risk of inflammatory bowel disease ( OR 17.6, 95% CI 3.6 - 51.6), but the number of observed events was small. The other factors examined did not influence the risk of inflammatory bowel disease. Conclusion: Maternal smoking during early pregnancy reduces the risk for the child to be hospitalized with a diagnosis of inflammatory bowel disease. Severe neonatal infections may increase the risk. Thus, some exposures during the fetal and neonatal period seem to affect the risk of inflammatory bowel disease later in life.